Adam wouldn't have been able to see Die Hard (1988) at Christmas time, because it was released the United States on July 15.
Takes place during Christmas in Philadelphia, but when Marvin drives up to the house, all the surrounding trees are full of green leaves.
Adam goes to see the movie Die Hard, which was released in 1988. Later, his uncle Marvin shows up driving a Miata, which wasn't released until 1989.
In this episode viewers learn that Lainey's mom up and left at Christmas time which is why they don't celebrate the holiday. However, in season 2 episode 23 "Bill/Murray" which takes place in May, Bill is upset over the 7 year anniversary of the day his wife left.
The movie Die Hard was already in theaters back in season 2 episode 1 "Love is a Mix Tape" Bev offers to take Adam to see it as a reward for the loving mix tape she believes he made for her.