Continuity mistake: In the play before the final touchdown play, the announcer says it's now second and whatever, but the down marker in the background is set to first down.
Continuity mistake: When Tidwell gets the wind knocked out of him at the Christmas Eve game, and he is lying in the end zone, he is clutching the ball to his chest. When the camera pans out to a distance shot, his arm is outstretched and the ball is lying off to the side. When the camera comes back in for a close up, it is clutched to his chest again.
Continuity mistake: When Tidwell is out cold in the endzone the ball is clutched in one hand against his chest. Within a couple of camera shots, the ball switches from left arm to right arm a couple of times.
Continuity mistake: After they return from their date, on the porch Jerry ties Dorothy's dress. A couple of seconds later the knot is entirely different.
Continuity mistake: In the scene where Jerry McGuire is giving his farewell speech to the large group of people at his agency, he unbuttons his coat. Throughout the speech, the coat continually buttons and unbuttons itself.
Continuity mistake: When Jerry arrives at Dorothy's house to take her out for dinner she is wearing a dress with a very high neckline. In the next shot of her the dress has a much lower neckline, and then changes repeatedly between the two dresses.
Continuity mistake: Jerry receives a fax containing Rod's contract. Everyone is angry at how small a salary it is, but Marcy gives Rod a lecture, and everything works out. When Marcy is talking, you can see the hands of one of the crew members in the glass of a poster in the background.
Audio problem: In the scene where Jerry and Dorothy are having dinner at a restaurant, Dorothy leaves the table to make a phone call. While she is on the phone the Mexican musicians come over to Jerry and start playing music at their table. At one point, the shot is on Jerry with the violin player standing behind him. In the song they are playing you can hear the sound of the violin playing, but at the same time the violin player standing behind Jerry drops his violin and is holding it at waist level while the song is still playing. Since he is the only violin player there is no way we should still be hearing it in the song.
Continuity mistake: When Dorothy and Jerry kiss on the sofa, her beer glass is still on the tray on the table in front of them. A shot appears with no beer in view. The tray is slightly out of shot but the top of the beer glass would certainly be in view. In a longer shot, the beer is visible again. Dorothy does not touch the glass between shots.
Continuity mistake: When Jerry and Dorthy are standing out by the U-Haul truck Dorthy walks to the front of the truck and Jerry takes a step to the spot where Dorthy was standing. He is still moving, but then there is a close up of him and he is not moving.
Continuity mistake: In the scene where Jerry is waking up to the clock radio at the loudest volume, isn't it strange that the sisters, only one room away, don't hear it and therefore could assume he's awake. Why they later are being surprised by his presence seems weird to me.
Other mistake: Towards the beginning of the movie Dorothy first "meets" Jerry by eavesdropping on his conversation with a woman in the airplane. But Jerry is located in first class whereas Dorothy is in coach. Going by her seat location it seems like she's sitting at least 10 rows from Jerry, plus the area that divides coach from first class between them. And Jerry is speaking in a soft voice. Add to that the drone that an airplane makes (even if not airborne) and it's highly unlikely that she would have been able to hear him, even if he was the only person talking in the plane (also unlikely).
Continuity mistake: In the scene where Tidwell comes into the hall and the reporters are yelling for interviews, you can hear someone yell, "Hey Cuba."
Continuity mistake: In the scene where Jerry is waiting for the fax about Tidwell's contract, there is a shot looking over the fax machine (from behind the machine) directly at Jerry's face. If you look at the back of the fax machine, there are no phone lines connected to it.
Continuity mistake: During the scene in which Jerry and Avery break up we see him comforting her right before she punches him. When the shot is from behind him you can see that he is holding her and stroking her face with his right hand. As the camera switches angle to face him his hands are now at his sides.
Continuity mistake: During the final game, before it starts there's a shot of a player warming up and throwing a ball. When the camera follows the ball, for a brief second we see that the bleachers are empty, but immediately afterwards several shots of the stadium show it's packed with people.