Although the Yankees score five runs in the top of the seventh inning, the Bronx Bombers lose to the Orioles, 3-0, because the score reverted to the last completed inning after the game is rained out. This rule will be changed in 1980, and the game today would have been suspended.

This Day In Baseball

On August 13, 1978 — Although the Yankees score five runs in the top of the seventh inning, the Bronx Bombers lose to the Orioles, 3-0, because the score reverted to the last completed inning after the game is rained out. This rule will be changed in 1980, and the game today would have been suspended.

Source:
Baseball Reference August 13
National Pastime
Retro Sheet
Hall of Fame
SABR Games Project
Replay The Game