When Alison hands Scanlon the info to find Lila, she tells him that Lila graduated in 1987, because she went to school with her. But Lila drove off to CA before graduation.
This episode breaks two cardinal rules of the Medium bible: 1. A ghost who has appeared to Allison multiple times in her life, appears to her in the final scene dressed as a waiter (ghosts must forever wear the clothes they died in). 2. The ghost, as waiter, serves Allison a cup of coffee and hands her the guest check, after which he takes the money she gives him (ghosts can't physically interact with the living).