Thread:Weedle McHairybug/@comment-1191892-20200203180054

In-jokes by their nature are fourth wall breaking because they reference the games as games. Some of the more distinctive fourth-wall breaks are of this type: most obviously, Zero and Snake's reaction to the Raikov mask in MGS3 is entirely based around you knowing about Raiden in MGS2. The fact that some are subtle enough to function as in-world information just means they're good in-jokes, ie unobtrusive to people who don't know what out-of-game information they're referring to.

The thing with the "music stopping" on the other hand is in-game: it's established there was music playing over the PA system in this specific case, and it's stopped. This is part of that weird "mind control music" plot road-bump that doesn't really go anywhere. 