The live diamondback rattlesnakes were let loose during a showing of the film Snakes on a Plane last Friday. No one was injured.
"One was found in the parking lot during the show, and the other in the movie theatre," a cinema spokeswoman said. "They were both removed, and no one was harmed."
The snakes were later released in the desert.
The movie is about a crate-load of escaped snakes that run amok on an airline flight, attacking passengers and crew.
"There were kids at the show, and it was actually very reckless," Russ Johnson, the president of the Phoenix Herpetological Society said.
"The snakes' bite carries a powerful venom that could have seriously injured someone," he added.