A lot of people on here claim there are “plot holes,” but after doing a lot of research, the common complaints against the movie can be countered. Firstly, it never says in the HP books when McGonagall was born. It never said on Pottermore when McGonagall was born (look at the cache files if you don’t believe me). It says in OOTP that she taught at Hogwarts for thirty some years and we know she joined Hogwarts after two years at the Ministry and joined the Ministry after schooling so it seems like you’d know the birthday. HOWEVER, the reference in OOTP is misunderstood. It’s not stating in total how long McGonagall has taught, just the consecutive years she’s taught. This is proved because: Snape says he taught for 14 years (1995-14=1981). BUT, in HBP, he tells Bellatrix that he had sixteen years of information when the Dark Lord came back (1995-16=1979). The most likely scenario is that he took a short break (maybe for a trial or remorse, I don’t know) from teaching and rejoined after Voldemort fell in 1981 or 82.
Secondly, you can apparate in Hogwarts. The Headmaster can lift the enchantment and Dippet DID for the Ministry of Magic on that day.
Thirdly, we don’t know how Aurelius was born. It is possible. There are a lot of possibilities. Just because Kendra was dead and Percival was in Azkaban (not necessarily dead) it does not mean that Credence CAN’T be a Dumbledore. We don’t know if Dumbledore EVER finds out about Aurelius so we can’t call it a plot hole until it actually is one.
Finally, we don’t know how a blood oath works yet. There could be a lot of reasons to use a blood oath rather than an unbreakable vow. For one thing, an unbreakable vow leaves scarring and that’d be annoying. Other reasons could be that you don’t want the other person to die. Seeing as Dumbledore loved Grindelwald and in a way knew he was evil, he would never want him dead (even after defeated in 1945 he imprisoned him). The blood pact most likely just deflects any spell cast (that could be how Ariana died, I don’t know), but it does not “break canon.”
I truly liked Fantastic Beasts and I’m excited to see where they take it next (besides Brazil).