Ooh, a question for a "Pyramid" freak. Yay!
There were a few times in the L.A. run where there had been 5 categories played and even though the one team had already lost, the other team still played the final category because it was either the 7-11 or the Mystery 7.
However, there were at least two instances where the game was decided after only FOUR categories and one of the two remaining categories was the bonus card. The first one I can think of was in the summer of 1983. After four categories, Jill Whelan's team had 6 points and Philip McKeon's team had 14 points. The game was technically over, but since it was the first day of the week and both celebs were new, Dick asked if they could play the last two categories for practice, forgetting that the 7-11 was still hidden on the board. When reminded of this, Dick asked Jill's team to try to find it. They chose the wrong category, but rather than have them play out the category they chose, Dick just went straight to Philip's team, who proceeded to play the 7-11 and win the bonus.
One other time that it happened was in the fall of 1987, in the Leslie Easterbrook/Harry Waters Jr. episode that's on the trading circuit.
Brendan