Defictionalization: People drink eggnog from the bowl in Wally World moose cups. You can buy them.
The Other Darrin: Russ and Audrey, as usual. Audrey somehow managed to age at a much faster rate than Russ since the first movie as well....
Though in the sequel, Audrey is once again played by Dana Barron who played her in the original 1983 film.
Dana Barron was 2 years older than Anthony Michael Hall in National Lampoon's Vacation, similar to Juliette Lewis' age difference to Johnny Galecki, so her being older is normal.
The Red Stapler: Quite a few items from the movie (like the Wally World eggnog glasses) are popular Christmas items and Clark's Blackhawks jersey (seen in the "Shitter was full!" scene) is popular with Chicago Blackhawks fans. It's not uncommon to see the occasional white Hawks jersey customized with Clark's name and "00" number on the back.