The Builders - S1-E2
Revealing mistake: When Basil smashes Manuel against the wall where the dining room is meant to be, we can see it is made out of cardboard. Notice how it begins to fall off, even though it is meant to be sealed and covered in wallpaper. (00:16:05)
Suggested correction: Perhaps this was due to O'Reilly's shoddy workmanship?
You could say that but Fawlty towers had wobbly sets all the time. I would say this would be covered under "mistakes".
Where is the 'codswallop' as you so euphemistically put it? To me it looks like O'Reilly cut corners by shoddily placing a sheet of plasterboard in the doorway without attaching it well then shoddily wallpapering over it. Hence the reason for it falling out.
Basil the Rat (a.k.a. Rats) - S2-E6
Corrected entry: When Basil, Polly and the Spanish waiter are talking in the kitchen, watch as Polly almost slips over on her high heels on rat poison.
Correction: It was a piece of veal covered in rat poison, and it was completely intentional.
Correction: Well there was rat poison wasn't there? People slip on and trip over things all the time.
The Germans - S1-E6
Character mistake: When the first German guest enters reception, he asks Polly, in German, if she would tell him what time lunch is served. She replies in German "at 9am, in five minutes." Which would be a strange time to be serving lunch! Actually her pronunciation of "9" sounds more like the German word for "no", so could be mistaken for "at no time. In 5 minutes."
Suggested correction: He asks what time lunch is being served. Lunch would not be served at 9am, it would be served around midday. Polly's response is "In no time. In 5 minutes" is absolutely correct. She does say "nein", not "neun" but it is not a mistake.
Corrected entry: When The Hotel Inspectors arrive at the end of the show, one of them describes the hotel as having 26 rooms. However in 'A Touch of Class,' Sybil says the hotel only has 22 rooms.
Correction: Manuel also has a room of his own. This would, using the logic in the correction below, bring the total to 27. Therefore, the original correction is correct and the number of rooms mentioned in the hotel inspector episode was a continuity error.
Correction: Sybil doesn't say the hotel has only 22 rooms; she says "22 rooms is the limit". She is talking about rooms available if any upper class people such as Basil is hoping for, ring up asking for rooms, ie she doesn't count rooms occupied by permanent residents. The Hotel Inspectors' "26 rooms" means all the hotel's guest rooms, so to the 22 we add on 3 for the Major, Miss Tibbs and Miss Gatsby, and one more room now available because Polly is no longer living in. (Note - in "Gourmet Night" Basil tells the ladies "You're supposed to be in your rooms", thus confirming they have separate rooms at this time, and in "The Germans" Polly states "I'm only here at mealtimes", confirming she has moved out.).
Correction: It is likely the Inspectors meant 26 rooms for guests - not counting Manuel's room nor Basil and Sybils'. However, Polly could've moved out by then (as we learn in The Germans), which would mean 26 rooms available for guests, even if three are occupied by long-term guests.
The Kipper and the Corpse (a.k.a. Death) - S2-E4
Corrected entry: The short elderly gentleman and the tall redhead bimbo are leaving the bar. After 15-20 seconds Basil is shown leaving the bar too. But Basil comes through the lobby before them.
The Kipper and the Corpse (a.k.a. Death) - S2-E4
Corrected entry: In the scene where Sybil is talking on the phone in the lobby about the short elderly gentleman guest and has tall redhead bimbo, just before the old man and his bimbo come in you can see the bimbo come past the corner of the office wall early, then stop, then start walking again on cue.
Plot hole: Sybil leaves the hotel at 05:29 and returns with Audrey at 24:39. 19 minutes have elapsed in real time during which Basil has been 'entertaining' Sybil's friends. So Sybil had just enough time to visit Audrey, talk to her and return. There wasn't enough time to visit the homes of Alice, Kitty or Virginia. Sybil went straight to Audrey who must therefore be her closest friend. Also Audrey was free and knew nothing about the party. Would not Basil have invited Audrey to the party? Is not Audrey's presence just to allow Sybil to explain to the audience when it makes no sense she is not at the party? (00:05:30 - 00:24:40)
Suggested correction: In 'The Wedding Party' the Major comments about Basil not liking Audrey, so maybe he didn't invite her. Or maybe she was in the uncomfortable position of keeping the secret for Basil despite seeing how upset Sybil was.
The Germans - S1-E6
Visible crew/equipment: When Basil runs from the restaurant and into the office, as the door opens to the hallway you can see a monitor in the office, showing what we can see. The director must be watching the action from in there.
Suggested correction: Most places like this are likely to have CCTV and the office would be the optimum place for the manager to watch on the monitor.
Visible crew/equipment: When Basil enters the "Private" room, the camera is reflected on the glass door pane.
Suggested correction: This is way too vague to be accurate. The office (which has private on both doors) is visited by Basil on innumerable occasions throughout this episode and so needs to be more precise.
Audio problem: Throughout the episode the picture Basil is distracted from putting up has no glass covering on it. However, when he smashes it at the end you can hear the distinct sound of glass breaking. (00:29:35)
Suggested correction: The sound isn't glass as you can see just as he goes to smash the picture there is no glass on the picture.