When Wednesday is gathering samples to test for a DNA match, she gathers a cheek swab, a mucus smear plus hair from Gomez's mustache and the top of his head. With all of those samples she should have matched with all, but the "WIG" noted by Gomez at the end of the film. Additionally, she neglected to take any samples from Morticia. Correction: If you look closely, Wednesday attempts to take all of those samples, but struggles to remove the hairs/mucus from Gomez's body. It is only the head hair she is able to retrieve, and only on a second attempt.
As in the previous film, Cousin Itt's name is again misspelled as "It."
After leaving Niagara Falls, before arriving in Sleepy Hollow, an Interstate highway interchange for I30 and I35E is shown. The only place this occurs is in Dallas, TX.
Both Gomez and Morticia make the common mistake of thinking that the Salem Witch Trials sentenced those convicted of witchcraft to death by burning them at the stake. They were, in fact, hanged. Medieval witch trials did sentence those convicted to death by burning at the stake.