Continuity: When the household moving trailer is full and the rear doors are closed, the latches are still open. In the next few shots, the latches are closed, and then open again.
Continuity: When the family is at the dog pound selecting Hubble, the size of the sandwich held by Bob the Dog Catcher alternates from large to small to large again between shots.
Continuity: As Owen throws the ball that Hubble almost catches, Connie is standing there with her mouth open as if she is already amazed by Hubble's ability to fly.
Continuity: When Barbara Anne's owner comes to the door to talk to Owen, she is holding a coffee mug by the handle. The next shot shows her holding the mug on the other (non-handle) side.
Continuity: Near the end of the movie, when Owen stands on the hill while the flying saucer appears, there is a close-up on his smiling face. He is first looking over his right shoulder, there is a cutaway to his family, and when they return to Owen the mirror image is shown, with him looking over his left shoulder.
Continuity: When the dogs return in the end, everyone is looking up with wide eyes and mouths. But the spaceship isn't visible until Owen turns his head.
Continuity: Hubble is surprised to hear that dogs do not rule humans, but he himself is being sheltered, fed and kept by them (also obeying tricks).
Continuity: When Owen is fixing the woofer, he accidentally cuts a wire. But the next time he is seen fixing it, it is unharmed.
Continuity: The sidewalk changes back and forth between shots as Owen is walking Hubble in the shopping district.
Factual errors: When Owen is trying to teach Hubble to play fetch and is throwing the ball for the other dogs, Nelly is always either at the back of the pack or not even seen. Italian Greyhounds, like Nelly, are built for speed and can run faster than most dogs. Most likely, if you were to throw a ball for a Bernese Mountain Dog (Shep, who was always in the front) and an Italian Greyhound, the greyhound would be way ahead of the Bernese Mountain Dog.
Factual errors: When Owen crosses off the last day in August on his calendar, he crosses the number 30 even though there are 31 days in August.