I've been playing around with BimapData, generating composite images on the fly because I'm too lazy to combine them in an image editor program
I noticed that the sprite drawn from the image cache key appeared in chrome, but not firefox.
I reproduced this on the Phaser Sandbox - Single Sprite Template in chrome and firefox by setting the create code to the following:
function create() {
var sprite = game.add.sprite(0, 0, 'phaser');
var testBmd = game.make.bitmapData(27, 4