In the scene when Rudy is looking for a ticket to the ND game, at one part they show him in front of a parking lot and there is a Ford Explorer 90's edition in a spot. Not that the year would matter since I don't think Ford was making Explorers in the 70's. Also, when he's looking to get a ticket, he walks by a kid wearing a number 6 jersey with the ND dome on the collar. They didn't got to these uniforms till the 90's.