These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternative Character Interpretation: Was the Postman crying at the end because he was defeated or were they Tears of Joy? If you look below, one of his reasons for hating Christmas was being put on the naughty list, so it's possible that he was touched that the penguins gave him a gift, even if it was raw fish.
Fridge Horror: So, is that mailman going to be trapped at the zoo, mistaken for a penguin and treated as such, unable to talk and tell people he isn't, for the rest of his life?
Jerkass Woobie: The Postman. The reason he hates the Christmas season is because it greatly adds to his workload. People who have to consistently work during Christmas can probably sympathize with him. Although, it is implied that the true reason is because he's mad at Santa for putting him on the naughty list.
Lawful Evil: The Postman may be trying to stop Christmas, but he always follows postal regulations.
Moe: Olive manages to be one and a strong character at the same time.