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
Mickey Mouse used to look different. I can see the vague resemblance between the older versions of Mickey and the kid's gas mask. The fact that they're for kids would have led them to want to lend a friendlier name to what's essentially a horrifying situation.
I found one of these in it's original box when clearing the loft of my then new house. It must have been very scary for kids to have to wear these, it gave my then 7yr old daughter nightmares.