Continuity mistake: When De Niro's character gets in the limousine with Lewis' character he has a hurt hand. He wraps it with a handkerchief. As the scene progresses the handkerchief disappears and reappears depending on the camera angle. (00:07:15)
Continuity mistake: When Masha removes her dress, the straps on her bra are crossed in an x just below her neck. In the next scene with Masha the straps run straight up to her shoulders. (01:30:15 - 01:32:20)
Continuity mistake: Rupert is checking his hair in the mirror before leaving for the scheduled call and the taping. He says his last words to Jerry; notice how the poor man has his jaw fully taped up. When Masha frees his mouth later, she has merely to remove a single piece of tape. You may assume that she did it off-camera at some point while she was preparing dinner; even in that case, it does not explain why in that aforementioned shot Jerry was fully taped down to his knees but had the ankles free, but when he makes his escape slapping her and when he is in front of the TV store at the end of the movie he is removing tape specifically placed around both ankles. She could have reason to remove some of the tape in advance but not to randomly tape parts of him left outside of the duct tape cocoon. (01:16:05 - 01:34:40)
Continuity mistake: FBI Inspector Gerrity introduces himself to "the King", he asks the obvious question "What is your name." The agent on the left of the frame has his arms behind his back, but in the next shot they are crossed in front of his belly. (01:26:30)
Continuity mistake: After walking past the Stage Manager (Jimmy Raitt) who did not take him seriously, Rupert Pupkin bumps into Cathy Long. Notice the man in a dark grey shirt that walks behind the piano, right of the frame. At the cut, the man has another guy in front of him that was not there in the previous shot. (01:24:40)
Continuity mistake: "The King" is on the phone with Mr. Bert Thomas, the producer. During the conversation, the extras on the street are recycled. Particularly obvious a man in red pants and and a white and red shirt, who passes by at least 3 times, and a woman with a black skirt and a pink top. (01:17:50)
Other mistake: Rupert almost got to the end of the cue cards when he flips too quickly the one saying "Alive", partially hidden behind another he is holding in his hand, showing the one saying "again" too early. So Jerry asks him to go back. And he does, only to bring then from behind "again." There is a small bit when De Niro is off-camera, but for this sequence to go as shown, he would have slipped to the bottom/the back of the pile the "again" card that was already at the top and then put in its place one of the two he had already in hand, the correct one, "alive." The fact that "again", that was at the top of the pile, is pulled from the bottom instead, makes no sense. (01:08:50)
Continuity mistake: Rupert seizes Jerry's hard candy tube and asks him; "Do you mind if I have one?" He is holding the packet almost vertically, at the cut he holds it horizontal. (01:04:35)
Continuity mistake: Jerry Langford removes the goggles his kidnappers used to blindfold him. Masha is holding the gun with a different grip between shots (left hand under the right wrist, one finger under the handle, followed by a more conventional grip, with a different distance of her thumb in the next shots). (01:04:10)
Continuity mistake: In the kidnapping sequence, Jerry enters the car leg first, and his right hand is the last part to get in. In the view from inside the car, he's in head first, body rotated differently. (01:03:10)
Continuity mistake: While he waits for the last word on his tape, Rupert has another dream sequence. He greets his old high school principal saying "Well how are ya?"; notice there's Robert De Niro's thumb popping in view in that close-up on George Kapp, but in the following wider shot, De Niro's hand is on the armrest. (00:41:55)
Continuity mistake: After the encounter with the cancer lady, Jerry is stalked by Sandra Bernhard. In his escape he traverse an intersection; people in the street and on the sidewalk change between shots. (00:39:55)
Continuity mistake: Rupert is daydreaming about Jerry loving the demo tape and inviting him to his country house. Jerry sits down at the desk and puts the tape back into the envelope in one single shot, resolute. When Rupert asks him if he can bring someone, there's another shot of Jerry Lewis reaching for the envelope and putting the tape in it. (00:38:05)
Continuity mistake: Putting away the autograph book, Rita says "Rupert, you have not changed." In this second part of the conversation, multiple times Rita's arms go from folded to uncrossed, and the glass like in the first part of the scene appears and disappears suddenly in and from her hand. (00:19:40)
Continuity mistake: Dining at the Chinese restaurant, Rita asks a fresh refill of her drink. Throughout the scene, the glass appears in her hand seemingly at random between cuts. Not just that; the level of liquid changes as well. It is particularly obvious when she says that the mystery autograph looks like signed by "a retard." (00:17:00)
Continuity mistake: Rupert reintroduces himself to the old schoolmate Rita. He gifts her with a rose; during this first part of the scene Rita's arm position and whether her palms face up or down changes between shots. (00:15:30)
Continuity mistake: In the first dream sequence, Jerry is taking one more sip of his drink when Rupert tells him "That's...the worst." His left hand is staying at the same level as before, but at the cut it suddenly dropped low enough to be out of frame. (00:11:35)
Continuity mistake: In his third interruption to Jerry trying to get back to his apartment, Rupert does not have in either hand the wallet he pulled the Pride and Joy picture out of. When he is shown turning around saying "Okay OK okay", he is holding the wallet. (00:10:35)
Continuity mistake: In a cringeworthy bit of prop comedy, Rupert hands Jerry the picture of his Pride and Joy; De Niro is holding the picture with the forefinger on top in the wider angle, but with the thumb on top in the close-up. (00:10:20)
Continuity mistake: In the intro, the protagonist is making his way through the crowd of autograph hunters. One of them asks him "Hey Rupert, who'd you get?" Rupert makes a dismissive gesture with his hand, at the cut he repeats it even when he had lowered his hand already. (00:02:05)
