Police are investigating after “foreign objects” were found in food at a cafe at Warner Bros Studios, in Hertfordshire.
Police said the objects were discovered on 17 July at the Leavesden site, before the food could be eaten.
Warner Bros said the objects were discovered in a kitchen at its Studio Tour.
The studios are where all eight Harry Potter films and other movie franchises including James Bond were shot.
A Warner Bros Studios spokesman said: “The food was discovered before the Studio Tour opened and did not leave the kitchen”.
“We are taking this matter extremely seriously, the safety of our visitors is our primary concern,” it said.
The police were unable to say what was in the food due to ongoing investigations.