During the Midland Lee game, right after Coach Gaines asks if Billingsley is mentally ok, You can see Midland Lee's #16 Quarterback on the field wearing a Riddell Revolution Helmet. The date in the movie was 1988 but the Riddell Revolution had first come out in the year 2000.
Midland Lee must have had their team uniform supplier use a time machine to aquire their player's equipment.