They do hand sex on a roller coaster
Just as your mind is trying to wrap around all this clock mischief, it's time for the infamous roller coaster scene. Burgeoning filmmakers: if you want to make a movie become the talk of a third-period Phys Ed class, take notes. First off, a girl-band version of "Wild Horses" is playing. Then Reese puts Marky's hand where she wants it while they're going up the roller coaster. So, you know, shit is building up. And as they’re going down, it's like... a release, or something? Even if you're in 10th grade and getting B-pluses in English, you can recognize that THIS IS A METAPHOR FOR AN ORGASM.
Oh, also: somehow, because of Marky Mark’s clock shenanigans, CSI Gil Grissom has to go out of town to save his marriage, so Reese tells Mark to come over. But he's like, "Sorry, I'm with the boys, and we've got to murder a bunch of people and page Chris Cornell, but I can stop by later." So she gives him the house's keypad code, which definitely won't come into play later. After entering the house as she sleeps, he takes her bracelet with the words "Daddy's Girl" engraved on it, and then they do sex. In case you're keeping track at home, this is the teenage-girl's-dad's-nightmare part.