Continuity mistake: When Eddie Valiant is in his office, and he examines the newspaper photo of Jessica Rabbit and Marvin Acme, the picture doesn't match the photos shown to RK Maroon earlier in the film, and neither does the original of the photo he looks at next. The photo shows an earlier, less sultry version of Jessica, in a halter-neck dress. (Jessica wears a strapless dress throughout the film). The DVD's Toontown Confidential special feature mentions that Jessica's look changed during filming, and the scene where Eddie takes down the Jessica photos and looks at the holiday photos of him and his brother was re-shot to show the new Jessica. Looks like they either missed the newspaper scene or felt that the view was so brief it wasn't necessary to change it.
Continuity mistake: As Eddy Valiant walks out of Maroon Cartoon studios in the beginning a hippo bumps into him, then walks away. About 7 seconds later you see the hippo sit on a bench causing the bench to collapse to one side and a man fly up. You can clearly see the rope that pulls the man up as well as the actual person holding the rope.