Plot hole: There is no reason for there to be sinks in the bathrooms. The cars may be able to use sinks just as they use toilets, but in the bathrooms they are too small and too inaccessible for any use.
Plot hole: When Puss is being sent to prison near the end of the film a shot is shown of Softpaws effortlessly holding a golden egg with one hand. However, back in the giant's castle none of them were able to carry a single egg without help.