Character mistake: When they exit the bowling alley with the dog, the dog is never put in the car, only the cage.
Character mistake: When Walter brings Cynthia's dog in the carrier to the bowling alley he refers to it as a Pomeranian while it is actually a terrier. Somewhat related, when the the Nihilists confront Dude in the bathtub, the dude refers to the ferret as a marmot. Walter later refers to the ferret as an amphibious rodent. Perhaps he was thinking of a mink.
Suggested correction: These were purposeful taxonomic (funny!) jokes.