I see no reason the rule should be any different in cash and tournament. In a tournament if the blinds were 1000-2000, there was a raise to 10,000, then a re-raise to 50,000, and the small blind stuck out 10,000 he'd have to leave that in the pot or call the 50,000. I see no reason to make a different ruling for the exact same scenario just because it's live or tournament.
As Stuart said, it is the player's responsibility to stay abreast of the situation and if he's not there are consequences.
Far fetched or unlikely as it sounds, what if it's an angle shoot? The guy can say call and stick out $10 to try to get a reaction knowing that if he sees somehing he doesn't like he can just say "Oh I thought it was $10" and he gets his money. If the other player doesn't look comfortable when he says call, then he can say "Oh it's $50? OK, I'll call anyway".