Continuity: When Michael Keaton is talking to his wife he picks up Froot Loops, then a second later he picks up Cheerios.

Continuity: In the scene when Doug brings number 2 home to the guest house, Laura drives up, number 2 pulls up the blinds and they both say hi honey to Laura. Then Doug tackles number 2. Then the guest house is shown from the outside, and the blinds are back down at a slant.

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: when the original Doug brings the concret 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.