Continuity: As Buddy walks out into the street at the start of the movie when the cat is playing dead, you can see several parked cars on the street behind him. When the van backs up to 'catnap' buddy, there are no parked cars. Then as the van drives off again, there is a different bunch of parked cars in the street.
Great sites
Mistakes
When the Russian Blue is in Luke's house, there is a shot where Butch is tangled up in the telephone wire but it should actually be mirrored since it was the reflection in the cat's eyes. See more...
Cats & Dogs (2001)
Directed by Lawrence Guterman, starring Alec Baldwin, Elizabeth Perkins, Jeff Goldblum, Miriam Margolyes, Tobey Maguire (add more)
Cats & Dogs mistakes
Continuity: It is clear throughout the movie that the dog that plays the character "Lou" changes from a male to a female. You can tell in different scenes when Lou is standing up, it's a male dog, and when Lou is laying on his back, belly facing up, it is a female dog.
Continuity: When the cats drive into the factory the same hubcap falls more than once from the car.