Police and coastguards called to rescue a man who was being beaten up on a boat got there to discover they were actors filming scenes for a drama. A passer-by called the police after seeing the man being attacked by three others on the boat moored on the River Medway at Rochester in Kent on Sunday.
Coastguards and police arrived at 1100 BST only to find it was all an act.
A Thames Coastguard spokeswoman said: "The actors must have been quite surprised when everyone turned up."
She added: "They were just going about their business, and a member of the public obviously got the wrong idea.
"But it must have looked quite frightening - like some kind of drugs incident."
A Kent Police spokesman said: "We challenged the film crew and confirmed to our satisfactions that no crime had been committed.
"It was an easy mistake to make - it must have looked realistic."