The plot is based on the switching identity of twins, set amongst palace royalty. In short, absolutely nothing is believable at all. One might argue believability isn't the point here - it's just a piece of swashbuckling fun. To that extent the film has its moments, with sword fights, character switches and cunning tactics, but that places it amongst many, most of which do it more intelligently.
Review of The Man in the Iron Mask
