When Rupert and Rita are at dinner, and he is showing her his book, the level of her drink varies considerably without her touching it.
Rupert is talking to Jerry in Jerry's limousine. Rupert bandages his hand with Jerry's handkerchief. In the next sequence in the car the bandage is missing. Following this Rupert's hand is again bandaged.
In the three scenes in which Langford is taped to the chair, the configuration of the tape changes dramatically each time.
In a wideshot Masha takes the tape off Jerry's mouth with her left hand, but in a close-up her right hand is pulling off the tape.
When Rupert is waiting by the payphone, the other phones are hanging down. But in the next shot one of them is in its right place again.
In the final credits, Paul Simonon's name is misspelled as "Paul Simmion" and Kosmo Vinyl's name is misspelled as "Kosmo Vynil."
The TV sets in the store display window near the end, where Jerry Langford angrily watches the end of Rupert Pupkin's TV appearance, are all tuned to channel 3. There is no TV station in New York City on channel 3 (two major stations, WCBS and WNBC, are on channels 2 and 4 respectively). However, channel 3 was (and is) commonly used for connecting video devices such as home computers and videotape recorders to TV sets. The film crew most likely rigged a videotape player to the TVs to mimic a network broadcast, thus requiring them to be tuned to channel 3--a small detail that most audience members wouldn't have noticed.
When Jerry is wearing the sweater that Masha knitted him, her reflection is in the mirror behind him and she is talking but her reflection's mouth is not moving.
When Rupert asks Jerry about the handkerchief, Jerry says "yeah" but his mouth doesn't move.
Camera/cameraman reflected in the closing glass door when the security guard escorts Pupkin out of the office.