In the SOUND OF MUSIC movie, since Max is actually on stage when the von Trapps escape, he might have plausible deniability later. I cannot imagine that Georg and Maria would have left him behind if they thought he would be implicated in their flight.
As for the nuns, mentioned elsewhere in the thread, no one knows (except the other nuns) that they tampered with the cars. And I imagine that no one involved thought the Nazis capable of murdering nuns for providing sanctuary. So, I can't really fault Georg and Maria there.