Ryan McAvoy said:
But if it was a set photo from some as yet unseen Wampa footage I'm trying to imagine how Luke would have fitted in. Did he have to do a bit of Wampa shooting between blowing up the AT-AT and getting to his rendezvous with R2 and his X-Wing?
This is specifically why I said that promotional photos can depict things that aren't in the film. Like, not even in the script. Just here's a gun, here's Mark dressed as Luke, let's take a picture.