Continuity mistake: J.T.T. is supposedly "getting back" at his brothers by scrubbing their toothbrushes in the toilet. He scrubs the green and yellow brushes quite vigorously inside the toilet bowl. Later on, when the three boys are brushing their teeth, J.T.T. is using one of the brushes that he put in the toilet.
Revealing mistake: When the boys go into the bear cave and all of the snakes are hissing, you can clearly see that one of the snakes is a rubber snake with a black stick attached to its head - the black stick is coming from a whole in the ground. It is not even a good snake, the 97 cent 'convenience store' variety.
Continuity mistake: When the brothers are showing the film, it shows different scenes where the brothers are attacked - the camera angles change. For instance when J.T.T. is on the moose antlers, his brothers are on the hill running. When they all watch the finished copy, there are about 3 different angles, even one from below and to the side!
Continuity mistake: When the boys are in the restricted area and the planes are firing at the rocks (or the boys, I'm not sure), they duck for cover. You can see the rocks falling in the background, and it's very obvious that they are in front of a screen because the rocks are falling in slow motion.
Continuity mistake: The boys are in the desert and they get back in the car because of the wild horses are coming at them. They decide to film the horses as they drive with them, in some shots the mirror is down, and then in some shots the mirror is up.
Factual error: When J.T.T. encounters the moose, the boys say it's a female with her young. Female moose don't have antlers.