When Mackenzie receives a phone call from Taylor giving her the flight details to London you briefly see that they are already written on her hand before she writes them down.
About the middle of the movie Mackenzie wakes up and finds everyone in the kitchen. Clementine hands her a cup of coffee. Next scene she has a plate of buns in her hand as well as the coffee.
When McKenzie and Clementine are walking down the street in town about a third into the movie and the female shop keeper comes out to greet them, she starts the conversation regarding the Inn Christmas party with a Scottish or Celtic(?) accent, then she leans in to hug McKenzie and when the shopkeeper picks up her lines again, the accent is VERY obviously gone.
When Mackenzie speaks to Santa on Harris's cell phone near the end of the film you can see that the phone is on the home screen.