Thor's hammer is called Mjolnir, but the director of the first Thor film, Oscar-winner Kenneth Branagh, apparently did not originally want to call it that. Writer Zack Stentz told Vanity Fair that Branagh "didn't like the name Mjolnir because it's difficult to pronounce."

Stentz said Branagh asked the production team, "Do we have to call the hammer 'Mjolnir'?" Branagh suggested calling it "Uru" instead, based on the metal it's made out of.