California Doubling: The first two films were shot exclusively on sets at Leavesden Studio outside of London rather than on location in the US and France. The third film used Leavesden for Bhutan and Germany but also hired a Vietnamese crew to do some background plates, supposedly in place of China.
Diagnosis of God: Eddie Redmayne stated that Newt is autistic, although since it's the 20s, he isn't diagnosed with anything.
Fake Nationality: Jacob, Tina, Queenie, annd Credence are pretty much the only American characters in the movies to be played by Americans; most of them are played by British or Irish actors. Central European Grindelwald has been played by an American and a Dane, while Leta Lestrange, who was born in France and raised in the UK, is played by an American.
God-Created Canon Foreigner: Pretty much everything that didn't exist in some form in J. K. Rowling's canon prior to the Fantastic Beasts movies and got included in them qualifies.
Refitted for Sequel: This series contains a few things Rowling originally had in mind for Harry Potter but didn’t make into the final product:
Credence is a reworking of an idea about a wizard who didn't get to learn magic until his adult years.
Back in 2005, she gave WB a list of working titles for the seventh book for trademarking. One of them was Curse of Nagini. This suggests her Was Once a Man story was originally meant to be introduced there.
Queenie's name probably came from the original draft list of the forty characters in Harry's year which had a Queenie Greengrass. She ended up being re-named Daphne.
Seraphina Picquery's name came from a teacher who was at Hogwarts in the original draft of the first book. He'd have been a ghost and was originally from France. Rowling scrapped the character and put Professor Binns in his place.
Eddie Redmayne and Callum Turner really do look like they could be brothers. So much that Redmayne's wife had noticed the resemblance long before Turner was cast in the series and said they should play brothers some time.
Joshua Shea who played teenage Newt in the second film also bares a striking resemblance to Redmayne.
Richard Coyle had been assumed from the moment he said he'd been cast in the third film in January 2021 to be playing Aberforth Dumbledore due to his resemblance to Jude Law. This had been reported by some fansites around the time of the first test screening in that May but wasn't officially confirmed until the first trailer came out in December.
Underage Casting: Callum Turner is eight years younger than Eddie Redmayne even though Theseus is nine years older than Newt.
You Sound Familiar: In the Canadian French dub, several voice actors also voiced characters in the Harry Potter films. The most notable example is Xavier Dolan being the voice of both Ron Weasley and Newt Scamander.
. This suggests her Was Once a Man story was originally meant to be introduced there.