Jack takes Randall to the Vietnam Memorial in D.C. and says that he was drafted in the war. However in later episodes its established that he volunteered to go so he could keep an eye on his brother who was drafted.
Randall asks Déjà if she likes Police Academy 4, referring to his family's Thanksgiving tradition from the first season episode "Pilgrim Rick". However, in that episode it is established that the family watches Police Academy 3.