A team has finished a game with 20-18-1 runs-hits-errors line 5 times since 1897, most recently Boston Red Sox on 31 May 1954. That is about one every 88,600 team-games.
Box score for the most recent one ↗
20-16-4 20-16-0 20-16-5 20-17-0 20-17-2 20-18-0 20-18-1 20-18-2 20-19-0 20-19-2 20-19-1 20-19-5 20-20-3
The whole distribution — Runs-Hits-Errors Lines · All 18 shapes