Continuity mistake: When Roger starts reading Marvin Acme's will out loud, Jessica takes her left hand and rubs his head, but once the shot changes her hand is nowhere to be seen. (01:35:05)
Revealing mistake: After Bongo the Gorilla Bouncer tosses Eddie into a pile of garbage cans in the back alley, Eddie lifts himself up and here we can see that he's wearing knee pads beneath his pants. (00:21:25)
Continuity mistake: After Greasy starts up the dip machine, the number of ropes tied around Jessica's midsection changes from two to three within a couple of shots. (01:22:30)
Continuity mistake: When Doom writes on the bar's blackboard "Rabbit Dip" the look of the text keeps changing all the time: sometimes it's neat, others it's fuzzy, and others some letters are missing. (00:52:10 - 00:53:10)
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: When Eddie pours out his whisky, the way he holds the bottle changes between shots. (01:06:35)
Continuity mistake: When the movie starts and Herman is launched outside the park, the rattle balls on the bars disappear. (00:01:25)
Revealing mistake: When Eddie fires his "Toon" revolver at the whisky bottle, you can see what appears to be a white, plastic model in his hands. This obviously would've been used as a reference for the animation to be tracked onto later.
Continuity mistake: The number of wood slats on Baby Herman's playpen keeps changing at the start of the film. When his mom says goodbye there are eight slats at the front, and five at the side. When he escapes the playpen there are eight at the side, and when Roger realizes the playpen's empty, there are nine at the side and seven at the front. Additionally, the characteristics of the teddy bear changes, as well as the colors of the balls on the wood slats. (00:00:40)
Continuity mistake: During Donald and Daffy's piano duel at the Ink & Paint Club, the grand piano's lid opens and closes on its own while Donald is performing simultaneously with his hands and tail. (00:16:40)
Continuity mistake: As Eddie sits at his desk and starts looking at the second Catalina vacation photo, his hands grip the stack of photos in different locations between shots. (00:26:20)
Continuity mistake: When Judge Doom cracks Greasy in the head with his cane, he lands in a stack of Acme eyeball boxes. Some of the boxes in the background change their positions and locations in alternating shots while Doom is talking about Acme's will. (01:17:10)
Continuity mistake: Check out the style of Eddie's shoes when he's flat on the floor of Droopy's elevator as it's going up. Notice how he's got a different pair on his feet minutes later while gazing down at Judge Doom's gun in the back alley. (01:11:30 - 01:14:15)
Continuity mistake: When Mr. Acme is killed with a piano, there's a cop next to a briefcase taking pictures of the crime scene. A frame later the cop is 1 meter away from the briefcase. (00:29:05)
Continuity mistake: When the weasels make their appearance at Mr. Acme's crime scene their car knocks some boxes off. From one angle they are all scattered next to the front bumper, but when the angle changes they're gone and have moved several feet to the right. (00:31:55)
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.