The eight-part franchise, based on author J.K Rowling's book, came to an end last year.
However, a mini-movie is now being shot at the Potter studios in Hertfordshire, reports thesun.co.uk.
Actress Helena Bonham Carter, who plays Bellatrix Lestrange in the movie, was seen shooting for character.
"The cast have really enjoyed getting back together - they are so tight-knit," a source said.
The movie will be shown at one of the two theme parks which are under construction. One of the theme parks will open in California by 2014, while the other will be ready to open in Japan by 2016.
Actor Daniel Radcliffe rose to fame after playing lead role of boy wizard while Emma Watson and Rupert Grint played his best friends Hermione Granger and Ron Weasley.