According to the official Major League Baseball rule book, baseball games “are to last 9 innings or two and one-half hours, whichever comes first.”

In professional golf, signing the scorecard is evidently of utmost importance. If a golfer does not sign his or her scorecard, he or she is disqualified from the event.

In the Olympics, racewalkers are mandated to have one of their two feet on the ground at all time.

In world football, goalies may be replaced during any point of regulation time or overtime, but not during a shootout. The only caveat to this is if the goalie gets injured.

In professional hockey, a goalie is prohibited from crossing the red line that marks center ice. Plenty of goalies have still figured out how to involve themselves in their teams’ offense, however.

MLB's rules state that if a ball becomes lodged in an umpire’s mask, all runners will advance one base.