MLB extra inning information for regular season games exists here from the 1920 season forward. All playoff games have the number of extra innings listed.
For the NBA reglar season games, all NBA overtime information exists here from the 1974-75 season forward, and some of the earlier overtime games are listed. All playoff games have the number of overtimes listed.
College basketball before 1979-80 only includes the NCAA Tournament games, and overtime games are complete only back through the 2003-04 season.
The NBA neutral games don't match the neutral game won-loss records found in Sporting News NBA guides.
These are being annotated here.