Thunderous explosions and blinding lights are an everyday occurrence at the studios that spawned Star Wars and Empire of the Sun.
But the special effects became a little too realistic when builders discovered what is believed to be an unexploded bomb.
Contractors working on removing the Mound, a pile of rubble and earth at the back of Elstree Studios in Borehamwood discovered the device this morning and called the police.
It was detonated during a controlled explosion and bomb disposal experts are now trying to work out whether it was a weapon or a prop from a film.
Chairman of Elstree Studios Councillor Morris Bright was astounded when he learned the device had been found.
He said: “I thought they’d dig up a few skeletons but never a bomb. You hear stories of bombs being found but don’t expect it to happen in your backyard.
“There is a possibility it could be a prop from a First World War Film the studios did in the 1990s, but experts think it is most likely to have been a bomb dropped in one of the world wars.
“We had to move quickly to detonate it as it could have posed a real risk to the hundreds of people working in the studios as these things become more and more unstable the older they are.”
He praised Hertfordshire Constabulary, contractors and studio staff who had worked quickly to make the situation safe, with a minimum amount of disruption.
He added: “Now we know the site is safe, it would be fascinating to know where the device came from as it could be an opportunity to find out a bit more about the history of our town.
“I wonder if anyone who was alive during the Second World War remembers whereabouts the bombs were dropped in Borehamwood.”