I’m sorry but you’re plain and simply wrong. This cover art could not be any more representative of the movie. It’s Hellboy, in the art style of the comic (It’s a comic book movie if you’re not aware), and Mignola was involved in the movie and had been in plenty of interviews.
It’s Hellboy, on the front of the steelbook, what the **** else do you guys want? Besides, this movie was primarily made for fans of Hellboy (not Del Toro Hellboy fans) and fans of Hellboy adore Mignola’s work, so the artwork couldn’t be any more perfect.