When Angel (Ron Perlman) jumps happy celebrating his uncle is finally dead, he cheers 'Merry Christmas' which has no sense since he 'killed' Jesus (Federico Luppi) in New Year's Eve. However, this is deliberate, as Angel is portrayed as an American who hates being in Mexico, so his grasp of Spanish is limited.
When Jesús searches for Aurora after she has taken the Cronos, as he walks through two doors, he stops. Behind him, reflected in the glass of the door, is crew and equipment.