In the article Emma is reading about Norma's death, Norman's age is given as 18. Yet in an earlier episode, when we see Norma and Norman's joint gravestone, it gives Norma's year of death as 2015 and Norman's year of birth as 1995. That would have made Norman 20 years old, not 18, when his mom died.
When Marion Crane checks into the motel she signs the register as Marie Samuls instead of Marie Samuels.