Mayans did not mummify their dead. Normally their kings would be laid out and covered with gold, jade, turquoise, or other types of adornments. They did not have sarcophaguses and Castle could not have seen a "mummy's face", if anything, he would have seen a face plate that covered the remaining bones of the king. A mummy, sarcophagus, and curse are all Egyptian, not Mayan.
Erick Avari also plays the head librarian in The Mummy (1999), dealing with a mummy's curse.
Erick Avari plays Rupert Bentley, who announces that the mummy is cursed. In season one, episode 13 of Leverage, The Second David Job (2009), he plays a museum employee who is tricked into believing that he is suffering from a mummy's curse.
One of the rare cases where the audience sees the victim for a few seconds before he dies, but with no clue as to the murderer.
Guest star Gil Birmingham ("Cacaw Te") and star Nathan Fillion are both from the Joss Whedon universe. Each had a role on "Buffy the Vampire Slayer". Birmingham had a minor role in a second season episode, and Fillion had a major recurring role in the seventh, and final, season. Navi Rawat (Rachel Walters, museum employee) was also part of the "Whedon-verse" as Dana, the psychopathic slayer in the final season of Angel (1999) episode 11 titled "Damage".