In the final basketball scene with Donna and Eric, Donna's pigtails go from lying on her shoulders to being caught on the neck of her shirt.
In the opening scene, in Eric's basement, Jackie wears a sweater with her initials "JSB" on the front. In the s2e5 episode "Halloween", Jackie's middle name is revealed as "Beulah".
Jackie wears a Rainbow Brite t-shirt in 1979. Hallmark introduced Rainbow Brite in 1983, and the first series episode aired in 1984. Hallmark licensed rights to Mattel, who first issued dolls, toys and other items in 1984. The first Rainbow Brite movie, Rainbow Brite and the Star Stealer, came out in 1985.
Right after Kitty picks up the basketball while talking to Eric in the garage, a piece of cloth swings in and out of view on the right side of the screen.
Jackie tells Donna that if Maria and Tony from "West Side Story" had played basketball one-on-one and Maria had won, they never would have fallen in love. Donna retorts, "And then Tony would never have been killed in that knife fight." Actually, Riff and Bernardo were killed in the knife fight, while Tony was shot by Chino later.