If you pause and read the Daily Bugle newspaper articles, you'll discover that the zombie outbreak in the future, might have originated from an elf who was carrying the virus and was eaten either by the Abominable Snowman or a sentient, possibly magical talking snowman.
The cause of death of JJJ's business partner, Adrian Toomes is listed as having happened "after a courageous battle with Natural Causes" which corresponds nicely with the blurb "Toomes died doing what he loved: Living".
The spirit who answers the phone when the Ghost of Christmas Present, Deadpool, calls "Banshee, Ghoul and Specter Services" identifies himself as Gef the Moongoose. Gef was allegedly a real spook who haunted an Isle of Man family in the early 1930s and was known to have a high-pitched voice.
The Ghost of Christmas Past, Dr. Strange, finally inquires as to how it's possible that JJJ is able to fall asleep after being visited by the ghost of his dead partner and is warned more ghosts are to follow. After dozens of remakes which failed to acknowledge as to how it would be possible to just fall back asleep after such a creepy encounter, it's nice to get a straight answer.
The conversation Deadpool has on the phone with the agency where he says "Okay" incessantly is based on the writer, Vaughn Smith's wife's telephone conversations.