When Sir Trenton first sees his son racing Stripes, his owner/carer has just started to undo his rug and does not appear to undo the front two straps. When he rears, the front two straps appear to be undone as the rug slips straight off his body.
As Nolan Walsh comes around the turn of his newly made corn field track and climbs off his tractor, there are no corn stalks on the ground. In the far shot of Channing hugging him, the ground is littered with stalks.
Every so often through out the movie, Stripe's head is very hairy and you can see the black dye or paint on his face. It isn't as dark as his normal color. The next clip, his hair is very short and dark black, with his normal wide stripes again.