zeph’s pop culture quiz #29

What is caused by using the switch?
    Just leave a comment with your educated guess—you can ask for additional hints, too. [Leaving a comment is easy; just click the ‘Leave a comment’ at the end of the post and fill in the form. If it’s the first time you post a comment, it will be held for moderation. But I am constantly checking, and once I’ve approved a comment, your next ones won’t be held, but published immediately by the system.]

UPDATE 1 (07 June 2012):

Now that I am ↵back online, here is a very direct hint, so that you finally can solve #29 …

UPDATE 2 (08 June 2012):
Hm, the above hint wasn’t strong enough, it seems—so here are two more. The first one is in more or less direct connection to the switch in question: What are they listening to?
 

 
The second one concerns the backstory told in flashbacks: Where are they coming from? Obviously they are rescued at sea. Where is the vessel, the crew of which is rescuing them in the screencap below, headed to? If you can answer that, you’ll know the title of the movie.
 

UPDATE 3 and solution (10 June 2012):

All right, now it’s been too long, here’s the solution:
    For his ‘↑Passage to Marseille‘ (1944) director Michael Curtiz reunited a substantial part from the cast of ‘↑Casablanca‘ (Curtiz 1942). Namely: Humphrey Bogart, Claude Rains, Peter Lorre, Sydney Greenstreet, Helmut Dantine, Corinna Mura, Monte Blue, Adrienne D’Ambricourt, Jean Del Val, Charles La Torre, Louis Mercier, Georges Renavent, and Hans Heinrich von Twardowski.
    Like in ‘Casablanca’ the Free French during World War II are at the center of the plot. Jean Matrac (Bogart) serves as a bombardier with a Free French bomber squad operating from the United Kingdom. By the switch depicted in the first screencap he releases the bombs from their bay. So, in a way, he switches destruction on. The second screencap depicts a German anti-aircraft reconnaissance detail listening for the Free French aircrafts approaching. All of this is part of the outermost timeframe of the movie’s narrative. Starting from there the background stories of Matrac and his close comrades are told by nested flashbacks. The third screencap stems from the second timeframe. Matrac, Marius (Peter Lorre), Garou (Helmut Dantine), Petit (George Tobias), and Renault (Philip Dorn)—all seemingly shipwrecked, adrift in a small boat in the Caribbean—are safed by the steamer ‘Ville de Nancy’ … on its way to Marseille. Aboard the steamer more flashbacks are told and the whole story unfolds …