Warning! This article contains SPOILERS for Teen Wolf: The Movie.There is one big Lydia callback in Teen Wolf: The Movie in how Allison's memory comes back in the film. Allison surprisingly comes back to life at the beginning of Teen Wolf: The Movie after her character had tragically died during Teen Wolf season 3. However, while Allison has quite literally come back from the dead, she appears to have lost her memory at the beginning of the film. The only thing that makes Allison's memory come back is hearing Lydia's banshee scream in a key moment in Teen Wolf: The Movie.

https://screenrant.com/teen-wolf-movie-allison-memory-lydia-scream-death/