Witness

Note: The bugs credited to "Infocom" come from the file bugs.mss, part of the source code release. If only we had such lists for the other games!
1. In version 13, you can GET IN just about any object, with numerous buggy results. You can GET IN CARVED CHAIR without Mr. Linder complaining, and thus be sharing the chair with him when he's shot. If you GET IN something you're carrying, then any reference to yourself asks which one you mean. If you GET IN ME, you can DROP ME. If you GET IN something after meeting Linder but before he takes you to the office, he follows you into it. When it's time to go to the office, he takes you out of whatever you're in. The possibilities are legion.
2. In version 13, you can GO THROUGH OFFICE DOOR to leave the office before the gunshot.
3. In version 13, even if the door is closed, you can go between the living and dining rooms, and from the tub room to the bathroom. --Infocom
4. In version 13, you can SEARCH another room FOR anything from a distance. --Infocom
5. In version 13, even if you're sitting down or hiding, you can still use some verbs on objects in the room that should be out of your reach: DRINK, EAT, ENTER, HANDCUFF, KICK, KILL, KISS, PHONE, PUT, RAISE, READ, SLAP, SMELL, TAKE OUTSIDE, WALK AROUND, and WALK TO. --Infocom
6. In version 13, even if Monica is handcuffed, she will play another record in her bedroom, and she will push you away if you try to TAKE HER OUTSIDE or take her shoes or feel her. --Infocom
7. In version 13, you can do things to the cat even when you're not in the office. --Infocom
8. In version 13, if you drop the handcuffs then you can't pick them back up. You're told, "You shouldn't release a suspect until your work is finished here."
9. In version 13, if you're not holding the handcuffs, but the clock key is present, then TIE MONICA TO LOUNGE says, "(with the clock key) She puts up a struggle, but you manage to do it." It also works with the set of house keys. If you don't have any of those things, then TIE MONICA TO LOUNGE says, "There's nothing to tie her with!", but she still gets tied up. The room description then includes, "Monica is fastened to the lounge with the ." Then UNTIE MONICA says, "Monica rubs her wrists as you take the . She refuses to look at you."
10. In version 13, if you're not in the office when Phong responds to Monica's ring, then you ring for him somewhere, when he gets to you, Monica says she was testing the wiring even if she's not there.
11. In version 13, if you ARREST an inanimate object, but not FOR anything, you get a gibberish message.
12. In version 13, if you're not in the office when Monica tests the button, you don't hear any bell and Phong doesn't go to the office. --Infocom
13. In version 13, if you ASK DUFFY ABOUT CORONER after he comes back, he still says he's called them and they're coming.
14. In version 13, when you're outside, LOOK DOWN says, "There's mud there, mostly.", even if you're on the paved peastone driveway or the small wooden deck outside Linder's office.
15. In version 13, GET something FROM MONICA that is in sight but not in either of your inventories responds, "He doesn't have it!".
16. In version 13, if you don't push the button before Monica fixes it, and you ask Duffy for a hint, he will not get to the hints in his list that follow the one about the button. --Infocom
17. In version 13, comparing the muddy and hidden guns doesn't tell you that one barrel is short. --Infocom
18. In version 13, if you don't go in the house, but you wait on the office path until Stiles is on the office porch, then call his name and go to the porch, he's described as though the shot had been fired. --Infocom
19. In version 13, if you don't go in the house, Stiles gives the wrong response to WHO AM I and WHERE IS something. --Infocom
20. In version 13, when Phong first lets you in, ASK FOR LINDER responds, "Mr. Phong isn't here!" instead of "Mr. Linder isn't here!" --Infocom
21. In version 13, if you're in the driveway when Monica goes through the garage, she's described as being "down the hall to the east" instead of "off to the east". --Infocom
22. In version 13, ASK MONICA ABOUT CANCER responds, "Dad gave it to me ..."! --Infocom
23. In version 13, the moon lights up the yard even after sunrise. --Infocom
24. In versions 13 and 18, you can get the chunk of putty or the piece of green wire before the window is broken, using EAT, READ, or LIGHT.
25. In versions 13 and 18, if you have the handcuffs and HANDCUFF MONICA where there's nothing suitable to handcuff her to, you get the message, "There's nothing to handcuff her to!" You still have the handcuffs, and she still moves around freely, but her state has changed somehow. After that, HANDCUFF MONICA says, "She's already fastened with the pair of handcuffs." If you drop the handcuffs and try to pick them back up you get, "She's not even tied up!".
26. In versions 13 and 18, you can push the butler's button while sitting in the carved chair, but only until Monica rewires it. After that you're told, "You'd do a much better job if you stood up."
27. In versions 13 and 18, in the kitchen, GET MIXER AND TOASTER gives no response. Several other pairs of untakeable objects do the same.
28. In versions 13 and 18, if you're in the hallway when Duffy and Stiles reach the living room, Duffy seems to disappear without notice. --Infocom
29. In versions 13 and 18, if you're in Monica's room when she enters, TIE HER TO BED responds "Monica isn't here!" --Infocom
30. In versions 13 and 18, you can talk to people even if you're hiding. --Infocom
31. In versions 13 and 18, if you try to look through a window and there isn't one where you are, the response refers to the car window. --Infocom
32. In versions 13 and 18, if the only wires in the room are the standard white and black ones, you can (for example) examine them, but trying to (for example) take them gets you "(You can't see the wire here.)". --Infocom
33. In versions 13 and 18, characters claim no knowledge of "the gunshot" and "Mrs Linder's suicide". --Infocom
34. In versions 13 and 18, some objectionable words ("bastard", "God", etc.) appear in the Tandy version. --Infocom
35. In versions 13 and 18, there is an error in the message for asking an inanimate object about an absent person. ASK TELEGRAM ABOUT MONICA says, "Monica can't hear you." Later versions say, "telegram can't hear you."
36. In versions 13 through 20, EXAMINE WINDOW gives the same description (including the white wires and electric relay) whether you're inside or outside the house, but EXAMINE WHITE WIRE says, "There's no wire here." when you're outside.
37. In versions 13 through 20, if you ASK PHONG ABOUT MONICA when neither is present, the response is "Monica isn't here!" instead of "Phong isn't here!". --Infocom
38. In versions 18 and up, if you interact with the keyhole in certain ways right before the hidden gun goes off (such as EXMINE KEYHOLE), the game considers you to be near enough to the keyhole that you always get shot. But this happens even if you're still sitting in the wooden chair, where you're usually safe. --Torbjörn Andersson
39. In versions 18 and up, you can GET CUFFS when you're already holding them. Each time you get the response, "You are now carrying the pair of handcuffs."
40. In versions 18 and up, in the rock garden, OPEN ROCKS says, "It's already open."
41. All versions have a serious bug in the use of IT. You can interact with objects you haven't even seen yet, using IT. For example, you can EXAMINE LIQUOR CABINET THEN OPEN IT, or FIND MYSTERY THEN READ IT from anywhere in the game. Another interesting thing to do is EXAMINE WOODEN CHAIR THEN SIT IN IT on the first turn. This doesn't get you inside the house, but Mr. Linder tells you his story and hands you the threatening note.
42. In all versions, although you can't GET objects inside a closed container, you can do just about anything else to them, as if they were visible in the room. If they're otherwise takeable, then you can even pick them up using EAT, READ, or LIGHT.
43. In all versions, the dresser in Linder's bedroom can be closed, but not opened.
44. In all versions, if you PUT something ON BED in Monica's or Phong's room, it's gone forever, unless you remove it using IT right after. If you LOOK ON BED, you see everything you've put on either of these beds. PUT something IN TUB has the same problem. If you PUT something IN CLOCK, it's just gone; you can't even see it using LOOK IN CLOCK.
45. In all versions, HANDCUFF MONICA TO something puts the cuffs in it. So if you HANDCUFF MONICA TO CABINET THEN OPEN CABINET, you "see a pair of handcuffs" inside it. HANDCUFF MONICA TO CLOCK or BED makes the cuffs disappear. After you do this, UNTIE MONICA picks them back up, but they don't show in your inventory. If they're the only thing you're holding, INVENTORY gives no output. If you DROP them they don't show in the room description, and you can't pick them up again.
46. In all versions, if you don't sit down in the wooden chair, there is a 50% chance that you get shot instead of Linder. But if you survive him, then SIT IN WOODEN CHAIR, he tells his story and hands you the note. --Torbjörn Andersson
47. In all versions, after Linder dies, if you say PHONG, GIVE ME THE GUN, he gives you the house keys. --Torbjörn Andersson
48. In all versions, a number of unexpected objects can be locked and unlocked. These include the mystery book, refrigerator, bathtub, dresser, and cupboard.
49. In all versions, if you try to LOCK or UNLOCK anything in the presence of the living Linder, he says, "Don't leave yet. We're just getting started."
50. In all versions, if you KNOCK ON a DOOR with someone on the other side, you get, "Someone shouts, "Go to the front door!"", unless it's the front door. In that case you get, "A muffled voice says, "Come in!"". This even works if you KNOCK ON FRONT DOOR from Entry when someone's on the porch, or if you KNOCK ON TOILET DOOR when Monica's in the toilet room.
51. In all versions, you can TELL anything visible ABOUT something, producing such responses as, "grandfather clock lets out a loud yawn.", or "broom appears to be getting impatient." You can also ASK anything visible ABOUT something nonexistent such as GREEN KEY or something not in the game yet such as TICKET, producing such responses as, "bed looks confused. "I don't know anything about any ticket!"".
52. In all versions, you can ASK any character FOR DRINK or CIGARETTE at any time, whether present or not. You can even ASK MR. LINDER FOR CIGARETTE when he's dead, and he smokes with you.
53. In all versions, you can EXAMINE CIGARETTE anywhere. You get, "All you can see is an ashtray full of butts."
54. In all versions, some commands can't act on the room you're in, For example, in the kitchen, CLEAN KITCHEN says, "(You can't see any kitchen here!)".
55. In all versions, the message saying you can't use multiple direct objects gets screwed up by disambiguation. For example, if you've found the powder and have all three guns, ANALYZE POWDER AND GUN asks, "(Which powder and gun do you mean, the hidden handgun, the muddy handgun, or the snub-nosed Colt?)". Answering HIDDEN gives, "(You can't use multiple direct objects with "hidden"!)". Answering MUDDY says, "(You can't use multiple direct objects with "muddye"!)".
56. In all versions, there is a bug in the letter you get if you ARREST MONICA AND PHONG with only minimal evidence. After explaining Phong's acquittal, it says, "While Monica could have conspired with him and aided him, she too was acquitted of conspiracy, because". The letter ends just like that, with no reason for Monica. Here's one simple way to trigger it: Get the gun receipt, push the butler's button after Linder's death, ask Phong about the powder, then once she gets back, ARREST MONICA AND PHONG. --Kay Savetz
57. In all versions, if you wait outside at the office porch for Stiles, then TAKE STILES OUTSIDE says, "[Foo!! This is a bug!!]". --Torbjörn Andersson
58. In all versions, you can get Sergeant Duffy to appear prematurely. If you ACCUSE MR LINDER OF SUICIDE immediately after he's been murdered, the game responds with:

    Duffy appears for a moment. "So you believe that Linder's death was suicide? I'm not convinced. But if you'll just "arrest Mr. Linder," we can go on from there." He disappears again.

    You will get this even though you haven't yet met Duffy. You will also get it if you've sent him away to analyze something. --Torbjörn Andersson
59. In all versions, WAKE MONICA says, "You wouldn't like that." --Torbjörn Andersson