Kylie Minogue was mistaken for a real waitress in her role in Doctor Who when a pensioner asked her for a cup of tea.
Kylie Minogue has been filming in Cardiff and Swansea
While filming a one-off Christmas special outside a Swansea hotel, an elderly customer apparently thought the singer was a member of staff.
The 39-year-old star plays a waitress on the Titanic in the BBC Wales show.
An eye-witness said: "It was absolutely comical. Kylie is an international star but obviously this old dear didn't know who she was."
He added: "She said to Kylie: 'Excuse me, love, is it too late for a cup of tea?'
"Kylie saw the funny side and just laughed.
"I don't think she knew if the lady was serious or not and just carried on into the film set."
The pensioner then walked into Morgan's hotel in Swansea in time for her tea.
The Australian plays a waitress called Astrid on the doomed ship alongside Tennant in the one-hour Christmas special called Voyage Of The Damned.
She and the Doctor, David Tennant - who was wearing a tux and bow tie for the scene - also filmed in the Exchange building neighbouring the hotel.
In the special, an alien menace dressed in a dinner jacket invades the 1912 launch party of the Titanic.
Fans were keen to see the action and Gary Owens, landlord of The Queens pub opposite, said: "People have been sitting in the pub looking out the window across at the set.
"Lots of people have been waiting around outside to try to catch a glimpse of Kylie.
"She's definitely been good for business."