Continuity mistake: A few seconds after Eddie makes the big turn in Toon Town's tunnel, his right thumb noticeably changes its position on the steering wheel between shots. (01:09:50)
Revealing mistake: When Toon Town's red curtain rises for Eddie in the long tunnel, the reflection on the pavement doesn't move correspondingly. (01:10:00)
Continuity mistake: Upon entering Toon Town and crashing into Jessica Rabbit's Packard Eight, Eddie's steering wheel rotates all by itself - as indicated by the spoke positioning itself between his hands all of a sudden. (01:10:35)
Continuity mistake: When Eddie crashes his car in Toon Town, from the inside we see that there's nothing in front of the car, but when the angle changes we can see a huge mess around with lots of people surrounding the car. (01:10:35 - 01:13:30)
Continuity mistake: After Eddie has crashed in Toon Town he gets out of his car and casts no shadow, and looks as if he's floating. Later on he does cast shadows. (01:10:45 - 01:13:30)
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)
Revealing mistake: After Lena Hyena plants a kiss on Eddie, he tumbles down the street and lands face-first onto a solid white line. Pavement is animated into this shot, however a reflection of the stage floor is still visible. (01:13:20)
Revealing mistake: When Valiant came upon the ugly Jessica look-alike, and she began to chase him, the chase ends with Eddie moving the roadline towards a wall, the results of which are her crashing into it. When Eddie throws the line to the wall, you can see that the cartoon line goes a bit "into the filmed wall" and covers a part of it. (01:13:30)
Continuity mistake: After fooling Lena Hyena with a road divider, Eddie's necktie blows over his left shoulder. But once the angle changes, his tie is suddenly hanging down again like normal. (01:13:30)
Revealing mistake: Eddie heads into Toontown with an oversized animated gun. As he lurks into an alley, his gun is a plastic prop. During filming, Hoskins would carry the prop gun and the animated gun would be superimposed over it, but the animation wasn't applied to the gun in the alley. (01:13:50)
Revealing mistake: Before Benny crashes into the pole while carrying Eddie and Jessica, they show a shot in front of it of him coming towards it, and you can see the pre-cut line in the pole where it breaks in half. This is better seen on the VHS version, it is harder to see on the DVD, but it's there. (01:16:10)
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)
Visible crew/equipment: A crew member's hand is visible turning the steering wheel of Eddie's beat-up Plymouth when Roger skids it to a halt. (01:17:35)
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)
Continuity mistake: After unveiling the dip machine, Judge Doom explains its functions while waving his cane in the air. But in the following shot his cane is planted firmly on the floor instead. (01:19:15)
Revealing mistake: Close to the film's climax, when Doom is showing off his Dip Machine, we see one of the weasels hoisting a canister of Dip up a ladder. If you look close, you can see a large wire pulling the canister up. This was seen in the VHS version and may have been corrected in the DVD, I am unsure. (01:19:20)
Continuity mistake: When Roger blasts out from beneath the Acme Factory grate, Judge Doom lifts his head twice in successive shots. (01:21:05)
Continuity mistake: After Roger springs onscreen from an underground pipeline at the Acme Factory, a steel grate is thrust high into the air, falling right in front of Judge Doom (however the shot cuts away half a second before it's supposed to hit the floor). But two shots later that same grate is seen falling from a much higher elevation again. It should have been lying on the floor at this point. (01:21:10)
Continuity mistake: When Roger goes to the Acme warehouse, he brings the gold-plated gun that was in Eddie's car after Eddie took it from RK Maroon. This is a real (not-animated) gun, and when Roger is talking to Benny before going into the warehouse, he's holding a real (non-animated) gun. After Roger bursts through the drain, the gold gun he's holding is animated. (01:21:25)
Revealing mistake: In the Acme warehouse, Roger's shadow disappears a split second before the bricks land on him. (01:21:50)
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.