But it was. Doesn't look a think like Mickey, though. World War II-era. Gas masks for kids during the Blitz. This one's in a war museum somewhere near flickr user psmithson: Swansea, maybe? I have no idea.
According to the fascinating wartime Disney blog, Toons At War, Walt actually cooked up a very Mickey-looking children's gas mask right after Pearl Harbor. It quickly ceased production, though, when the military requisitioned all the rubber for combat use.
Baby Gas Mask in psmithson's flickr pool [flickr]
Mickey Mouse Gas Mask [toonsatwar.com]
Previously: Israeli-designed infant gas masks and respirator tents in MoMA's "Safe" exhibition