It depends on the mistake. I mostly gm and when I. A player it's usually in support of a new game for a fellow permagm friend who probably isn't making it by mistake or it's in support of a former player of mine who is just starting out.
In the first case it's usually a situation where sanity checking yourself if you aren't sure is seen as ok so it would need to be a pretty big goof or a silly mistake that would persist like telling a player "a 1handed longs word is like a d ten" to bring it up at the table. If I think knowing the slip will matter I might mention it between games.
With the second type I'm usually surrounded by people who consider me their gm even if that other guy is trying to gm. Under those circumstances I make it a point to deliberately avoid correcting any rules unless asked. If a player asks about something beyond our sheets I might even deflect saying "it depends on Bob what do you think Bob?" type things since back seat gm'ing is pretty rude & it's easier to avoid if I just make an effort at maintaining a hard line.
I have one player who plays fast and loose with the rules as a player and regularly thinks he's going to win some victory by calling me out expecting some phenix Wright type win ut the results are pretty universally "no the rule does not work like that" or "yea the shambling Mound that jumped off the cliff onto Alice does indeed take 8d6 damage... Roll them bob.. Wow xx is a lot. The shambling Mound takes xx and so does alice... Oh alice is down?... The shambling Mound is pleased with bobs assistance" the gm deliberately ignores rules in favor of the plsyers regularly with good reason and correcting them in the moment is rarely going to be beneficial in the long run .
In the first case it's usually a situation where sanity checking yourself if you aren't sure is seen as ok so it would need to be a pretty big goof or a silly mistake that would persist like telling a player "a 1handed longs word is like a d ten" to bring it up at the table. If I think knowing the slip will matter I might mention it between games.
With the second type I'm usually surrounded by people who consider me their gm even if that other guy is trying to gm. Under those circumstances I make it a point to deliberately avoid correcting any rules unless asked. If a player asks about something beyond our sheets I might even deflect saying "it depends on Bob what do you think Bob?" type things since back seat gm'ing is pretty rude & it's easier to avoid if I just make an effort at maintaining a hard line.
I have one player who plays fast and loose with the rules as a player and regularly thinks he's going to win some victory by calling me out expecting some phenix Wright type win ut the results are pretty universally "no the rule does not work like that" or "yea the shambling Mound that jumped off the cliff onto Alice does indeed take 8d6 damage... Roll them bob.. Wow xx is a lot. The shambling Mound takes xx and so does alice... Oh alice is down?... The shambling Mound is pleased with bobs assistance" the gm deliberately ignores rules in favor of the plsyers regularly with good reason and correcting them in the moment is rarely going to be beneficial in the long run .