The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Hastings, Japp (for some reason) and Poirot are at the movies; when the camera pans through the room, there's a guy sitting behind Hastings, while behind Poirot there are a red haired woman and a man, as confirmed by the close-ups. When the music stops and Hastings tells Poirot that he can open his eyes, the couple have moved behind Hastings. (00:02:50)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: During the party, the establishing shot shows everyone in the small circle Poirot is a part of having a glass of champagne. That includes Mr. Robinson. As Poirot puts on the tray his own glass, someone's hand reaches over for another - it can only be Mr. Robinson's, as his wife is wearing gloves, but he never put down his own glass. (00:06:05)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: In the first scene with the 'G-Man', the room in the shots with the camera roughly by his shoulder is lit in a different way, with his body fully in the 'sun'. Especially visible when he picks up the phone and starts spouting yankee-isms going all "Yeah yeah so what yeah." (00:09:00)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Poirot knocks at the door of The Black Cat, next to a street worker and a pimp. Nobody is walking down the street in the wider shot, but in the close-up an elderly couple passes by. (00:22:55)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Poirot is doing his round of phone calls at night clubs looking for the chanteuse; the pen before Hastings' arrival is pointed to the left side of the screen, when he sits down (and Poirot has not touched it) it points to the right. (00:24:40)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Miss Lemon, as Penelope Maitland, enters the performer's room. The shady character that opens the door does it holding a cigarette in his left hand. The hand is kept close to his chest in one shot, while it's on the door in the reverse. (00:31:35)