Audio problem: We establish that the manor Deeds stays at makes an echo when you shout or yell. Yet when Deeds slides down the banister and crashes into the table, his very loud yelling and the smashing into the table never produces an echo.
Factual error: When we see Deed's Uncle being lifted off the summit of Mount Everest, you see him holding onto a very spiky and rocky summit. The summit is not like this at all. It is, in fact a much rounder shape, and not rocky. It is permanently covered in snow, therefore being something your body can get around and hold onto. (00:02:05)
Continuity mistake: When Deeds is in the pizza place before he finds out about his inheritance, Murph is standing there with him holding a blue Pepsi cup. It switches to Deeds then when it is back on Murph, he is holding a beer mug and he continues to hold this throughout the scene.
Continuity mistake: The cats falling from the burning building change color from the time the hit the trampoline to when they reach their final destination.
Continuity mistake: Deeds hands Crazy Eyes the french fries and Oreo pizza in the box. The shot cuts to Cedar and Cecil for two seconds but when the shot cuts back to Crazy Eyes, the slice of pizza is already in his hand. No way could he have opened the box, took out the slice and have it in his hands in just two seconds. (00:11:45)Casual Person
Other mistake: When Deeds is rescuing Miss Keeling's cats, there are two mistakes. There are smoke and flames inside her apartment - both of them should be coughing a lot from the smoke. Oxygen gets displaced in a fire. Second mistake is why isn't any of the fireman inside the building coming up to her apartment or even fighting the fire? There is no way any fire dept or police dept is going to let bystanders just walk up to the scene as Deeds and Pam did.