In the scene where Wade backs up the car to pick up Plucky on the road when Plucky wanted to tag with them badly, the gear shift lever appeared to be mounted between the driver and passenger seats; but in every other shot, the gear shift is mounted on the steering column and the whole front seat is a bench seat, which the car seats up to 6 occupants at the most.
Hamton happens to have vomited on the comic book that Plucky just bought (though the perspective was only shown outside the car since it is considered repulsive to show characters vomiting, and this was only heard in dialogue); but in a later scene, the same comic book is clean and like new.
In the final scene when everyone returns to Acme Looniversity, Calamity, Mary, Furrball, Li'l Sneezer, and Vinnie were wearing their skating clothes during the lyrics "We've been outdone!"; yet in the next few seconds, the skating clothes and Vinnie are gone and Mary is back to her usual clothes.
The USA DVD cover depicted Babs, Buster, Dizzy Devil, Elmyra, Hamton, and Plucky riding on one of the rides on Happy World Land; yet in the actual movie, only Plucky along with Hamton, Wade, Winnie, and Uncle Stinky went to Happy World Land while all of the other characters took different adventures.