Revealing mistakes: In the film, MacPherson is an ABOVE knee amputee, but the prosthesis that is shown on numerous occasions is for a BELOW knee amputee.
Continuity: In the scene when MacPherson is getting a ride from the day worker, the truck is loaded with lumber, etc and the tailgate is open when he picks him up again after making a stop at the job site. Then after a cut the truck's tailgate is closed. Then after another cut when they get close to the address MacPherson is seeking, the tailgate is open again with the lumber sticking out.
Continuity: In the flashback when MacPherson gives the copy of Watership Down to Miguel, it's signed "Thanks, McPherson", instead of "Thanks, MacPherson".