There were two new referees in 1974, Cal Lepore and Gordon McCarter. Lepore replaced the retired John McDonough, the referee for Super Bowl IV and the NFL's longest game, the 1971 Christmas Day playoff between the Dolphins and Chiefs which lasted 82 minutes, 40 seconds. McCarter succeeded Jack Reader, who left the field to become chief lieutenant to NFL Director of Officiating Art McNally at league headquarters in New York.
The following changes were adopted to add tempo and action to the game  and to help counter the proposed changes announced by the World Football League to their games:
One sudden death overtime period (originally 15 minutes; since 2017, 10 minutes) was added to all preseason (up to 2019) & regular season games; if no team scored in this period, the game would result in a tie. This rule was enacted to decrease the number of tie games. The first regular season overtime, a September 22 game between the Pittsburgh Steelers and the Denver Broncos, ended in a 35–all draw. It was not until November 10, when the New York Jets defeated the New York Giants, 26–20, that an overtime game would produce a winner. Since the 2012 season teams each get one possession to score unless the team first possessing the ball scores a touchdown or yields safety.
Goal posts: moved to the end line from the goal line, where they were since 1933. This was to reduce the number of games being decided on field goals, and to increase their difficulty, as well as to reduce the risk of player injuries. They were last placed there from 1927 to 1932.
Missed field goals: The defensive team takes possession of the ball at the line of scrimmage or the 20-yard line, whichever is farther from their goal line. (In 1994, that reference to the line of scrimmage was changed to the kick spot, which is usually seven yards behind the line of scrimmage.) Notice that the 20-yard line is where the defense takes possession after a touchback.
Kickoffs: moved to the 35-yard line (from the 40-yard line) to reduce touchbacks, promoting more excitement with kickoff returns, through 1993 and since 2011. From 1994 to 2010, the kickoff was moved farther back, to the 30-yard line.
Punt returns: members of the kicking team cannot go beyond the line of scrimmage until the ball is kicked, except the player at the farthest end of each side of the snapper ("gunners"). The original rule change would have prohibited any player from crossing the line of scrimmage prior to the ball being kicked. The penalty is the same as that for an ineligible player downfield on a pass play.
An eligible pass receiver could only be contacted once by defenders after the receiver has gone three yards beyond the line of scrimmage.
When the defensive team commits an illegal use of hands, arms, or body foul from behind the line of scrimmage, the penalty will be assessed from the previous spot instead of the spot of the foul.
The penalties for offensive holding, illegal use of hands, and tripping were reduced from 15 to 10 yards.
Wide receivers blocking back towards the ball within three yards from the line of scrimmage may not block below the waist.
In addition to the on-field rule changes, the league eliminated the "future list" of players a team could sign without placing them on an active roster. The future list had been formalized by the league in 1965 and had informally existed for over a decade before that. The concept would return in 1977, renamed the practice squad.
From 1970 to 2001, there were three divisions (Eastern, Central and Western) in each conference. The winners of each division, and a fourth “wild card” team based on the best non-division winner, qualified for the playoffs. The tiebreaker rules were changed to start with head-to-head competition, followed by division records, records against common opponents, and records in conference play.
Note: Prior to the 1975 season, the home teams in the playoffs were decided based on a yearly rotation. Had the 1974 playoffs been seeded, the AFC divisional matchups would have been #3 Pittsburgh at #2 Miami and #4 wild card Buffalo at #1 Oakland; the NFC matchups would not have changed, although #1 Los Angeles would have had home field for the NFC championship game due to its head-to-head victory over #2 Minnesota in week 11.
The Buffalo Bills replaced their standing red bison helmet logo with a charging blue one with a red slanting stripe coming from its horns.
The Kansas City Chiefs switched from gray to white face masks. The arrowhead logo on the helmets shrunk in size, while the black border on the arrowhead became thicker.
The Miami Dolphins modified its helmet logo so that the sunburst was centered on the dolphin's body instead of its head. Several players wore this logo during the 1973 playoffs and Super Bowl VIII.
The Philadelphia Eagles switched from white to green helmets, and added sleeve stripes and trim to the numbers. Pants changed from white to silver.
The San Diego Chargers introduced new uniforms, changing their primary color from sky powder blue to royal blue. The helmets were also changed from white to royal blue, and the players' numbers on its sides were removed. In addition, the face masks were switched from gray to yellow.
The Chiefs and Chargers were the first NFL teams to wear face masks in a color other than gray.