Lee Norris (Mouth) does not appear in this episode.
Nada Surf makes a special appearance and performs on the show.
This is the first appearance of Craig Sheffer
(Keith Scott) in season 3 and his first appearance since "Lifetime Piling Up
Lucas: (voiceover) H. L. Mencken wrote, "Every normal man must be tempted at times to spit upon his hands, hoist the black flag, and begin slitting throats."
(Brooke and Lucas are listening to Haley and Nathan's fight from the bedroom)
Nathan: (off-screen) Haley, what if something happened? That would have changed our lives forever!
Haley: (off-screen) Like what, marriage?!
Brooke: Ooh, she's good.
Karen: You are almost 18 years old and I'm almost 36 years old and if you do the maths it's pretty obvious what my concerns are.
Lucas: Mom, we didn't do that. We're being careful, more careful than you know!
Karen: It's more than being careful with the chemistry, Lucas, it's about being careful with your heart.
Lucas: Like you are with Keith? I know, you're right Mom and I get it, but maybe if you're always looking for reasons not to be with somebody, you'll always find them and I guess in some point, maybe you should let go and give your heart what it deserves.
Nathan: Did you think about it? Having a baby to stay together.
Haley: Nathan, I am 17 years old, we're still in high school. You and I are both in limbo. No, I don't want to have a baby.
Dan: You finally grew a pair of balls.
Keith: I always had a pair Danny. Just ask your wife.
Haley: And if you're so worried, then why didn't you stop us? It's just as much your responsibility as it is mine.
Nathan: You're right. It is my responsibility. Let me see the pills.
Haley: I cannot believe you still don't believe me. I can't believe it. Here take them. I don't need them anymore.
Haley: Your future as a basketball player is totally secure. Your future as my husband, not so much.
While Nathan and Haley are arguing about birth control, Haley takes out a blue bottle of water from the refrigerator. Later when Haley gets her pills out of her purse, the bottle changes to green, then back to blue when she gives the pills to Nathan.
When Keith and Lucas are throwing the football around, Lucas' iPod headphones disappear.
When Nathan walks into the old gym, the part of the wall that Nathan will later start painting when Whitey tells Dan to leave is already painted.
The episode title "Return of the Future" refers to the return of Keith to Tree Hill. In future episodes, Keith and Karen are able to rekindle their relationship and ultimately will become engaged, making Keith the "future" that is returning in this episode.