Just over 43 minutes into the movie, when the dachshunds climb up on the bed with Fran, it is clear that one of the puppies is a male. Early in the movie, all of the dachshund puppies are said to be female.
When Brutus chases Sgt. Carmody he tries to open the door to his car but it is locked so he is forced to climb a tree. The next morning Mark Garrison sees the car and opens the driver's door and it is not locked.