Continuity mistake: When Michael Keaton is talking to his wife he picks up Froot Loops, then a second later he picks up Cheerios.
Visible crew/equipment: In one scene in the dining room or kitchen with Michael Keaton, you can see the camera with a red light, along with the cameraman, reflected in the glass doors of a china cabinet.
Continuity mistake: When the original Doug brings the concrete worker to fix the house for Laura, Keaton uses a red sweater with a number one on it, and a white t-shirt under; But a couple scenes later, when he is talking to number three Doug and eating a sandwich, the white t-shirt has disappeared.
Revealing mistake: When Doug 2 wakes up and sees Doug 1, Michael Keaton's body double is noticeable in the angle shot from behind - he has bulkier hair.
Continuity mistake: When Doug is in the boat and sits up and starts talking about his life, he sits upright against the cushion, but after he says "I wasn't in it", he's leaning back.
Continuity mistake: When Doug 2 wakes up, his head is either above the pillow or below, depending on the shot.
