Source: Total Football: The Official Encyclopedia of the National Football League (ISBN0-06-270174-6). pp 1583–1592.
The definition of a drop kick, field goal, and punt is modified: all three can only be attempted from behind the line of scrimmage.
If a foul by a player causes an injury to an opponent, a team time out will not be charged to the penalized team anytime during the game instead of only during the last two minutes of a half.
The game clock will not start until the next snap following any change of possession, even if the player went out of bounds.
Officials will immediately blow the play dead when a defensive player is offsides before the snap and clearly rushes beyond the offensive line in such a way that he becomes an unabated threat to the quarterback.
A touchback will be ruled when a player fumbles the ball in the field of play and it goes out of bounds in the opponent's end zone.
A touchback, not a safety, will also be ruled when a player fumbles the ball in his own end zone and the opponent is the one that knocks the fumble out of bounds in the end zone.
An offensive player cannot deliberately bat a backward pass forward.
Art McNally resigned as the league's Director of Officiating during the offseason. He had held the position since 1968. Longtime NFL referee Jerry Seeman, who worked the previous season's Super Bowl XXV, was named as McNally's replacement.
Jim Tunney retired after 31 years as an NFL official. He remains the only referee to have worked consecutive Super Bowls (XI, and XII).
Gene Barth died on October 11, 1991. For the remainder of the 1991 season, NFL officials wore a black armband on their left sleeve with the white number 14 to honor him.