Excited children were left in tears and parents outraged after a trailer for a horror film was shown before a screening of a Peppa Pig film.
Adverts for psychological horror Ma and frightening superhero movie Brightburn were shown at the Empire Cinema in Ipswich.
Trailers of the movies, which do not yet have an age rating, appear to show dead bodies, suggestions of violence and a violent child in a scary mask.
The planned showing of Peppa Pig: Festival of Fun was then screened as advertised.
A spokesman for the cinema chain apologised and said it was investigating how the “inappropriate” trailers were screened.
A spokesman for Empire Cinemas said: “As soon as the staff on site were made aware of the situation, the programme was stopped and trailers were taken off-screen immediately.
“We do sincerely apologise for this and for any distress caused and will be reviewing our internal procedures to ascertain how this came to being.
“The film (Peppa Pig) did then go on screen as planned.”
Mother Charlie Jones, who works for the BBC, had taken her daughter, two, and 10-month-old son to the cinema for the first time.
The 34-year-old said she tried to cover her daughter’s eyes when the trailers came on. She said her daughter has been “really subdued” since the experience and asked about the mask in one of the trailers.
“There were lots of kids crying and she was very confused and started crying too,” said Ms Jones.