Newt was cleared and never charged.
A MACUSA document in an official companion book shows Newt was never actually expelled from Hogwarts. Dumbledore defended him and his name was cleared before he was expelled, so his wand would not have been broken.
NOTES: Proposed expulsion from Hogwarts School of Witchcraft and Wizardry due to the illegal possession of a ...
Apparently, "all will become clear". Or so says J.K. Rowling.
The truth is, as for now we don't know why Newt apparently gets to keep his wand, even after expelled. There are some fan theories, but nothing official.
Q. Why was Newt allowed to keep his wand & do magic, and work for the ministry? Hagrid had a different experience after expulsion....
It may be a specialized spell Newt uses.
As the Fantastic Beasts series is still in progress, new information may be added to the franchise either invalidating or further validating this theory. However, so far in the series Appare Vestigium is only cast once, by Newt.
“NEWT leads JACOB through the statue and into Magical Paris. He puts his case down and ...
In Chapter Ten of Prisoner of Azkaban Lupin explicitly states that the Whomping Willow was planted the year he started at Hogwarts:
“They planted the Whomping Willow the same year that I arrived at Hogwarts.
As that was many years after Newt attended Hogwarts, the tree in question cannot be the Whomping Willow.
No, the Whomping Willow was not there.
In the official screenplay, where Newt and Leta were is referred to as Bowtruckle Island. There is no mention of the Whomping Willow being present whatsoever.
“EXT. HOGWARTS LAKE, BOWTRUCKLE ISLAND—FOURTEEN YEARS PREVIOUSLY—EVENING
NEWT finds LETA sitting by the lake, tearstained, eyes swollen. They look at each other.
If you are talking about the scene where Newt is showing Leta a Bowtruckle then no, it is just a random tree:
Here is the Whomping Willow for comparison:
Not to mention that they would have been in trouble if they were standing next to it.
He may have wanted his escape known.
Escaping while Abernathy took his place in the prison cell would certainly be more effective in allowing Grindelwald to escape unnoticed. However, Grindelwald may have actually wanted it known that he had escaped. After throwing Spielman out of the carriage, he threw a wand after him, giving Spielman a chance to save ...
In order to escape prison, Grindelwald and his acolyte Abernathy switch places. Grindelwald could have run off with the vial, allowing his replacement to rot in jail. But Grindelwald's loyal followers are not yet so numerous that he can afford to waste them. To do so might send the wrong message to other followers.
When Madame Picquery reminds "...