Revealing mistake: Although Michael is pouring cereal out of a box labeled Kellogg's "Frosted Flakes", the flakes do not have a white coating, indicating they are regular corn flakes. (00:20:37)
Continuity mistake: During breakfast, the amount of milk in the bottle changes (decreases, increases, and increases again). (00:24:39 - 00:25:23)
Continuity mistake: The location on the table where Michael (John Travolta) set the cereal box changes when there is a wide view. Michael set it down past the milk with the side not aimed toward the salt and pepper shakers; later, the box was closer to Michael - between the milk and sugar bowl - and the side was aimed toward the salt and pepper shakers. (00:24:41)
Factual error: After the fight in "Joe's", Michael, Frank, Huey, and Dorothy were arrested on multiple charges and confined in the same jail cell plus the dog was also allowed to stay with them. The police officer shut off the lights and left the arrestees alone overnight in the cell; a jail would have officers/staff present at all times. (00:50:19)
Revealing mistake: In many scenes, particularly the dance scene in the bar, Michael's wings disappear and/or reappear. If you look closely throughout the movie, his wings are often completely gone.
Continuity mistake: When Michael brings the dog back to life, he first is shown standing on either side of a row of plants, the next shot he is standing between them. He did not move at all.
Continuity mistake: When they are in the car driving to Chicago, the rear view mirror seems to appear and disappear at will. When the view is of the inside of the car looking back, the mirror is not there. When the view is of the inside of the car looking forward, the mirror is there. When seeing the car from the outside, the mirror is there again....
Visible crew/equipment: When John Travolta is fighting the bull, the boom mic drops into shot.
Continuity mistake: Immediately after the bull fight scene, Michael is in the field talking to his friend, who is wearing a tie. In the scenes shot from the front, the wind has blown his tie over his left shoulder. But in the scenes shot from the rear, the tie is not hanging over his shoulder. When they cut back to the front shot, there is the tie, still blown over the actor's left shoulder. Cut again to the rear shot, and no tie on the shoulder. This happens all through this scene.
Continuity mistake: When Michael is leaving the milk bottle motel with the others the sun on the floor changes between shots.
Continuity mistake: When Frank and the others are to see Michael in the car the sun changes between shots.
