Deliberate mistake: Before Eddie turns on the band machine in the factory, we see Smart Guy holding a real gun. Three shots later, when the weasel is backing away in surprise, he is holding a toon gun, which later switches back to a real gun. (01:23:30)
Revealing mistake: When Eddie sits on the bench and the hippo sits down, you can see Eddie bounce off the bench before the bench even moves. (00:09:10)
Continuity mistake: Near the end in the Acme Factory, the weasels tunnel through the wall and say "Toontown is on the other side of the world, boss". Understandable because of the portal link between the two "dimensions". But while the wall they're tunneling through seems to only have about ten layers of bricks, when the Red Car crashes through it, it alternates between one layer of bricks to three and back and forth. (01:18:00 - 01:32:30)
Revealing mistake: When Roger takes a shot of bourbon and blows his top, it causes most of the glass objects in R.K. Maroon's office to bust into pieces. In some instances you can see an explosive charge breaking the glass - like the giant angel statue at the center of R.K.'s trophy collection. (00:24:00)
Revealing mistake: Just before a conveyor belt drops the vase upon Eddie's head, an overhead shot shows him pointing at Smart Guy, but actually Eddie points much further left in relation to where Smart Guy is standing. (01:25:10)
Continuity mistake: At the beginning when Baby Herman tries grabbing onto a clock's swinging pendulum, he stands on a box of Acme deadly mouse poison. But when the box falls over onto the countertop, its label vanishes. (00:02:40)
Revealing mistake: After shooting their way into Eddie's apartment, the weasels start walking in and cast long shadows on the floor. But the only shadow visible in a reflection on the nearby glass doors is that of Wheezy's Tommy gun. (00:41:10)
Revealing mistake: A string is visible suspending Greasy's gun when Smart Guy orders everybody to search Eddie's apartment for Roger. (00:41:55)
Continuity mistake: Baby Herman opens the faucet and floods the kitchen, but 2 seconds later there is no trace of the water. Since the rest of the mess that Herman and Roger cause (scattered cutlery, broken objects and furniture) does appear at the end of the gag when toon and real world combine, some trace of water should be seen somewhere. (00:02:30)
Continuity mistake: During the first animated Baby Herman scene, he throws away the lid of the cookie jar on top of the fridge. When the fridge crushes Roger, the cookie jar has not only managed to move from the fridge to the floor in a nano second, but also the lid is back on. (00:03:15)
Other mistake: Three shots after Eddie stuffs the soap into Smart Guy's mouth, when the other four weasels notice him tumbling down the stairs, a chair can be seen flying across the room. This is impossible, because the other four weasels are together, and Smart Guy was talking with Eddie, so there was nobody to throw the chair. (00:42:15)
Continuity mistake: In the climactic scene where the Red Car is about to "Dip" Roger and Jessica, one shot of Eddie (shot upward from the ground) also includes the hook that Roger and Jessica are hanging from. However, Roger and Jessica are not animated into this shot.
Revealing mistake: The streetcar railway tracks are simply metal strips laid in the road. When Eddie jumps off the back of the streetcar's bumper, you can see that the rails are not in full contact with the road, as there are visible gaps between the rails and the road surface. What's more, the rails do not have the grooves that would be necessary for the cars' wheel flanges. (00:10:10)
Continuity mistake: The toon patrol car hits the 2 police motorcycles in the middle of the long alleyway, yet after they crash the cops then land in the middle of the street. (00:59:25)
Revealing mistake: When Eddie is using the magnet to pull Judge Doom toward him, you can see the wires attached to Doom's shoulders used to move him. (01:27:05)
Continuity mistake: In the scene where Valiant gets his check notice he puts it in his left chest pocket, but when he gets in front of the trolley operator to pay he reaches in his left jacket pocket then it quickly shows him holding it showing the trolley operator. (00:08:55 - 00:09:55)
Audio problem: In the scene where Valiant is outside and looks over to see the brooms cleaning, notice the bird on the bike coming towards the camera. You hear a bell ringing as he goes by but there is no bell on the bike. (00:09:10)
Continuity mistake: When Eddie pours out his whisky, the way he holds the bottle changes between shots. (01:06:35)
Continuity mistake: When Eddie hears his friend has been laid-off, Delores puts her hand over the glass to remind him he needs to have the money by Friday and she takes her hand off the glass when the camera pans up to her face. When it cuts back to Eddie her hand is still over the glass. (00:12:00)
Audio problem: In the scene where Hoskins and Roger are going into the sceret room Dolores says, "oh swell," but her mouth doesn't move. (00:44:00)
Answer: There's really a lot of possible reasons he hates other toons. There's a whole Roger Rabbit book and comic book series that explain Doom's background more. In the film, he's greedy and wants to destroy Toon Town to build the freeway to make more money. In human disguise he's also seen as merciless and is just punishing toons to maintain law and order, etc. Although that's just an excuse to kill toons as well. However, not explained in the film; as a toon he was cast as the antagonist in cartoon films until an accident one day left him thinking he was an actual villain (as opposed to just an actor playing one). That's when he began his life of crime, including killing Teddy Valiant. So his hatred of toons is more about him being evil and not a personal vendetta against them, like Blade's motives.