The stunt occurred during a promotion for the movie "Iron Man 3" last weekend at the Goodrich Capital 8 Theaters in Jefferson City. Actors appeared at the theater, including some dressed as officers and one as Iron Man. Another actor was wearing what appeared to be assault gear and carrying a rifle.
Some moviegoers were frightened and called 911, recalling the shooting in July at a Colorado theater during the premiere of "The Dark Knight Rises." That attack killed 12 people and injured dozens others, and authorities said the gunman was dressed in police-style body armor.
Management of the Jefferson City theater apologized on the theater's Facebook page, saying it was meant to be part of the entertainment. They noted that similar dress-up promotions have occurred at past movies.
"We apologize and are sympathetic to those who felt they were in harm's way with our character promotion for Iron Man 3," the Friday posting read. "We didn't clearly tell our customers and some people didn't realize it was for entertainment purposes only."
A phone message left with a regional manager for Goodrich Quality Theaters, the chain that owns the Jefferson City cinema, was not immediately returned Friday afternoon.
Police also were upset, initially believing they were responding to a potential active shooting situation.
"Everything was in place - it's the opening night of a superhero movie, it's somebody walking in all-dark clothes - everything pointed to bad things about to happen," Capt. Doug Shoemaker told KMIZ-TV in Jefferson City. "There's really no good that can come of this."
Shoemaker added that it was a good thing off-duty officers weren't in the theater, because they may have confronted the actor, potentially creating a dangerous situation.
"It's an unfortunate lack of wisdom in this particular judgment that hopefully will never occur again," Shoemaker said.
The theater said steps have been taken to ensure it doesn't.
"Security and safety for our customers in our number one priority," its Facebook posting read.