In his moment of clarity, Leo mentions that he "may have been in the Navy". In Long Away (2005) (s8e6), it will be revealed that Leo once drove a supply truck and was awarded the Purple Heart during the war.
In Eric Gets Suspended (1999) (s2e9), Hyde and Fez go on blind dates with Patty and Mary. By the end of the episode, Hyde is with Patty and Fez ends up in a hot tub with Mary, where he finds out she has a boyfriend. In this episode, Patty appears again, but this time as Fez's girlfriend.
Eric and Kitty go to see Annie Hall (1977), a movie released in 1977. It starred and was directed by Woody Allen.