When 'Sinter' first meets Charlotte, he says he doesn't have a full grey beard, because he dyes it. But the ends are grey and the roots are black, which is the complete opposite of what would happen if a man dyed his beard.
Nick mentions a penguin doctor on the North Pole. Penguins live on the South Pole.
When young Eddie is narrating his letter, he says his dad fishes for "bass, trout, and shad" but the letter is written "bass and shad and trout"
Charlotte is too young to be sitting in the front seat.