the new Holgas have a different film mask inside (it comes with 2, one for 6x6, the other for 4.5x6). they hold the batteries in place now. people who have batteries rattling around in their Holga *most likely* took the plastic mask device out to get "better vinetteing". But yeah, you never know what the next surprise will be with a Holga. Part of the attraction.
Holga Buzz