Continuity mistake: As Max is carrying a birthday cake out of the kitchen, the candle blows out as he walks. But the candle is suddenly lit again when the camera angle changes, as he walks into the living room.
Continuity mistake: In the first film, "National Velvet," the Pie, Velvet Brown's horse that ran in the Grand National, was a gelding (neutered). In the sequel, the Pie has somehow become a stallion again and sires a colt many years later that Velvet's niece names Arizona Pie.