I posted a game earlier this week which illustrated different (in time and place) conventions about how to handle the end of the game, and passing.

Here is another, wierder example, which possibly is still relevant to modern play, as it is from 1999. It was a Kansai Ki-in game, and the report said that after move 338 Imamura could have claimed the game for an illegal ko capture - the two passes apparently being ignored. But this also seems to imply that an automatic loss for an illegal move has to be claimed, so it is not really automatic, despite what the rules say.

Maybe the players were just tired after a very long day's play.