Three Letter Codes

In the third video, Dad reveals a code on the bottom of his sock:

The three zeroes were found to correspond to the three letters after the hyphen on each person’s envelope. These letters are an airport code.

Each individual’s code is for an airport that is exactly (or close to exactly) on the same latitude or longitude as their ZIP code.

Snowman
On the back of the snowman was a sign that said “Does anyone have directions to TNM?” This was a hint to focus on the  directions  between each ZIP and its corresponding airport.

Results
This helped us open the directional lock on the chest of comics. Using Corn Holes's XXXX0 marking, people with a zip code ending in the same number need to go a specific direction to the airport they were given (i.e. 0 need to go north to get to their airport.). Putting this in order 0->9 gives a 10 direction combo, to match the 10 question marks. This opened the directional lock on the comic book chest.