NOTHING gets past those HP fans.

HBO has performed a swish and a flick in order to quickly remedy two major errors which appear during the 'Harry Potter 20th Anniversary: Return To Hogwarts' special this new year.

Hitting screens on New Year's Day (via Sky TV and NOW in Ireland and the UK), the reunion special saw the majority of the cast of the franchise wear their time-turners, travelling back to when they were part of one of the biggest movie franchises of all time.

Emma Watson, who played Hermione Granger in the series, was one of the more prominent actors to appear during the special, but some eagle-eyed fans were brought out of the magical journey due to an error made during the edition process.

During a montage of old pictures and footage of the actor, years before she was cast in the iconic role, one image stood out for all of the wrong reasons - it wasn't Emma Watson. Instead, editors had accidentally used a shot of actor Emma Roberts as a young girl.

Roberts originally uploaded the picture onto her Instagram in February of 2012 with the caption "Minnie mouse ears!".

HBO producers have remedied their mistake, saying in a statement: "Well spotted 'Harry Potter' fans! You brought an editing mistake of a mislabeled photograph to our attention. New version is up now."

However, this isn't the only 'Harry Potter 20th Anniversary' error. As every Potter fan will know, the characters of Fred and George Weasley were quite the trouble-makers, sometimes switching places with one another (often at the frustration of their poor mother). And so, HBO accidentally continued this tradition by switching the actor's names, Oliver and James Phelps, during their pieces to camera.

Uploading a screenshot of himself and his twin brother appearing on the special, Oliver Phelps posted on Instagram: "I guess after all those pranks over the years somebody decided to get their revenge. It was fantastic to be part of the HP reunion. Hope you all enjoyed it. #ReturnToHogwarts"

Tom Felton, who played their nemesis Draco Malfoy in the series, jokingly commented underneath the image: "It was my doing :) #weaslebee"

'Harry Potter 20th Anniversary: Return To Hogwarts' is available via Sky and NOW in the UK and Ireland, and on HBO max in the US.