Continuity mistake: When Regina tells her boyfriend to put the leash on the dog, he goes to do so but when you see his hand clip the leash on, the shot changes to a woman's hand clipping the leash on (the nails are covered in nail polish).
Continuity mistake: At the carnival, when the boy is standing in line for tickets, the girl he likes has her hair hanging straight. In the next shot, it's tied back in a ponytail.
Continuity mistake: At the beginning of the film when they all get into the 2 cars. Beethoven looks out of the window, the camera cuts to a back view of the dog then to the front again. Now he has a tennis ball in his mouth that wasn't there before.
Continuity mistake: In the opening of the movie, the little girl asks if they are late. When the family gets into the cars, she's not there.
Continuity mistake: Near the start, Beethoven goes into Ryce's room and begs for her to play ball. She is holding a violet top, but when she turns around to face Beethoven, it is black.
Answer: This takes place some time after the first movie so the dogs from the first movie were most likely adopted or reunited with their proper owners.