On connaît la chanson

In the unapproximate center of "On connaît la chanson," find a marvelous joke that missed by everyone at the sold out SFIFF screening I attended. If you want to try to catch it yourself, then don't read on! I'm writing to those of you who didn't or won't catch it. Four or five characters are seated chatting or arguing, I forget, round a table in a busy restaurant. As you know from other comments here, the script incorporates line fragments from well-known French songs (kind of like those "hidden picture" puzzles in the dentist office magazine). As each occurs, someone bursts into song. One of our group, after an unremarkable, perfectly conversational pause, says "je ne regret rien," then pauses, as does everyone else round the table. They look at one another, everyone at everyone, the very clatter of the restaurant seems to pause, waiting, and for the only time in this film, nobody takes the cue. Nobody breaks into the Piaf standard.