Stores which broke a worldwide embargo for the release of The Lord of the Rings: The Two Towers DVD face an investigation from the film's distributor.
The Two Towers is the second film in the Tolkien trilogy
Retailers across the UK were selling the DVD on Friday - it was supposed to go on sale on Tuesday - after a supermarket put the film on its shelves at midnight.
Fans of the film wrote to BBC News Online saying they were able to buy The Two Towers in stores on Saturday, despite advertising that it would not be available until Tuesday.
Entertainment In Video, the DVD's distributor, told the Times newspaper on Wednesday the stores had sold the film "without our consent".
"We are appalled that the release date could not be kept, and we will be reviewing our trading relationship with the party responsible," said sales director Paul Evenden.
'Ready to sell'
A spokesman for retail chain HMV said it was one of the last to decide to sell the DVD on Friday.
"Alongside other retailers we decided we were at a commercial disadvantage and we started selling it," he said.
"We are a specialist retailer, and we feel very strongly about having these guidelines from the distributors. It allows us to process the product properly and have it ready to sell on the correct date."
The DVD and video of the first of the Tolkien trilogy, The Fellowship of the Ring, has gone on to sell more than 2.5 million copies in the UK alone.
HMV's spokesman said that other retailers' decision to break the embargo could mean problems in getting stocks of future releases early enough to process.