There are no actual Dutch Christmas traditions shown.
Oliebollen (not oliebols) are not a Christmas tradition. They are eaten to celebrate the end of the year and the start of the new year. They are however already for sale during Christmas.
'Poffertjes' is pronounced correctly, but what you see is not a poffertje, it looks more like a British crumpet.
There's no actual Dutch bread in Ann's Dutch bakery.
The big white and red stars hanging in the mill workshop are not Dutch Christmas decorations but Scandinavian.
At 41:47, a male character talks about a 3-legged stool he had made as a child, reminiscing about it having a wobble. It is mathematically impossible for a 3-legged object to wobble. He proceeds to walk over to the stool and demonstrate its wobble, which it does; however, its legs are off-screen, so the actual number of legs is unknown.
Lily Jansen's outfit is not Dutch, it looks to be more Scandinavian or German.
A 'kerststol' would have a 'spijs' filling inside. On screen you just see dry bread.
In half of the outdoor shots, the windmill's wings are pointing in the wrong direction. The wings should always turn in the direction of the wing shaft, not the direction of the sail.
The dutch don't call this type of mills windmills, they are just called 'molens', mills. A windmill is usually the modern ones that make wind energy.
In the Christmas Market Bake-off scene at 47:46 the Jansens present the major with a single "poffertjes" that just appears to be a giant sugar cookie. Poffertjes are basically small pancakes (around the size of a US Silver Dollar) - they are usually served warm in batches of 19 with butter and powdered sugar.
Missed opportunity to pronounce 'Jansen' correctly.