Revealing mistake: As soon as Eddie walks into the Ink & Paint Club to see Donald and Daffy on stage, a shadow of one penguin's drink tray is cast on the wall near stage left. However, the penguin's shadow isn't animated into this shot. Instead what we can see is a shadow of the pole, which was used by puppeteers to carry the tray around the club before any animation took place. (00:15:00)
Revealing mistake: In the shot where Roger looks out of Eddie's apartment window to see the weasels approaching, you can see how their animations overlap the window sill as they cross the street. (00:40:20)
Revealing mistake: In some shots with the red cars, such as when Benny, Eddie, and Roger are about to crash into one, look at the wheels. The trucks appear raised with a third, large wheel in the center, obviously a road vehicle outfitted to look like a streetcar.
Revealing mistake: When Eddie's Plymouth skids out from R.K. Maroon's lot, a large section of the Red Car's railway track gets torn from the pavement with the greatest of ease - revealing that the track is actually just a set of metal strips laid out in the center of the road. (01:07:40)
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.