Note: Contains major spoilers for Fantastic Beasts: The Crimes of Grindelwald.

Fantastic Beasts: The Crimes of Grindelwald features enough Harry Potter lore and unexpected twists to keep fans happy for some time (the two years until the sequel comes out, perhaps?).

Related: How Fantastic Beasts: The Crimes of Grindelwald lets down its female cast

It also includes a surprise cameo – a familiar face we didn't expect to see in the Wizarding World of the 1920s, who may cause a bit of a mess for Harry Potter canon.

Irish actress Fiona Glascott (Brooklyn) has a brief cameo as a teacher at Hogwarts who Dumbledore puts in charge of his students when he receives a visit from Torquil Travers, Head of the Department of Magical Law Enforcement.

But she isn't just any teacher, she is Professor Minerva McGonagall, stern but beloved Harry Potter character and future headmistress of Hogwarts. (Played by Dame Maggie Smith in the original films in case you really needed reminding.)

FilmMagic / Gilbert Carrasquillo Getty Images

A fun little cameo, yes, but it poses a problem for the Harry Potter timeline.

It has been established already that McGonagall was born in 1935. Crimes of Grindelwald is set in 1927, making her minus eight years during the events of the film, a bold claim even for the most powerful witch. Unless the Ministry of Magic permitted her to use a Time Turner to travel back a decade or two to help cover some lessons...

Warner Bros.

This isn't the only Harry Potter plot hole to open up thanks to the events of Crimes of Grindelwald, which also raises questions about the events and timeline of Dumbledore's relationship with Grindelwald.

As JK Rowling delves deeper into Harry Potter's complicated past, the likelihood of contradictions and confusions only increases. It might be time for her to invest in her own version of Lucasfilm's Keeper of the Holocron.

Fantastic Beasts: The Crimes of Grindelwald is out now.

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