A question about the heroine's injury

[ending scene: Tree and Carter are at the restaurant, watching Danielle's interview on TV. Tree's cellphone rings]

Tree Gelbman: Hey, Dad. Dad.

David Gelbman: Tree, are you okay? Are you hurt?

Tree Gelbman: Dad, no, Dad. I'm fine. I promise.

David Gelbman: Are you sure?

Tree Gelbman: Yeah. Just a little scratched up.

David Gelbman: All right.

Tree Gelbman: Okay. I'll see you soon.

David Gelbman: I love you.

Tree Gelbman: I love you, too. Bye.

[Tree closes her cellphone]

Carter Davis: So, uh, now that your bedroom is officially a crime scene and all, where are you planning on crashing?

Tree Gelbman: [chuckles] Is that an invitation?

Carter Davis: You sure you wanna wake up in the dorm room again?

Tree Gelbman: Only if it's yours.

Carter Davis: Only of course, you'll have to sleep in Ryan's bed.

Tree Gelbman: [smiles] Of course.

Carter Davis: Yeah. We can, you know... oh, uh... I almost forgot.

[Carter takes Tree's bracelet out of his pocket and hands it to Tree]

Carter Davis: You left this little guy.

Tree Gelbman: Thanks.

Carter Davis: Hey, you know what your little scenario reminds me of?

Tree Gelbman: What?

Carter Davis: Uh...

Tree Gelbman: What's that?

Carter Davis: "Groundhog Day". The movie "Groundhog Day"?

Tree Gelbman: [shakes her head] I don't know.

Carter Davis: With Bill Murray?

Tree Gelbman: Who's Bill Murray?

Carter Davis: [surprised] Are you kidding me? "Ghostbusters".

Tree Gelbman: [shrugs] Sorry. I... I don't know.

Carter Davis: How do you sleep at night? You've never seen "Groundhog Day"?

Tree Gelbman: No.

[Tree storms into her room. She hastily starts packing her belongings]

Lori Spengler: She finally rolls in...

[Lori looks at Tree, puzzled]

Lori Spengler: Going somewhere?

Tree Gelbman: Yes. As far away as possible.

Lori Spengler: Tree, what's wrong?

Tree Gelbman: [continues packing] Me. I was wrong. I thought that if I stopped running that I could beat it. But it's never gonna stop.

Lori Spengler: Tree, you're freaking me out.

Tree Gelbman: Hello, that's me, a freak!

[Lori takes the cupcake, lights the candle, approaches Tree and hands her the cupcake]

Lori Spengler: [smiles] Tree. Tree, look. Happy birthday.

Tree Gelbman: [turns her back to Lori] Thanks. But I already ate it last night.

[suddenly, it dawns on Tree who is the murderer. She stops packing]

Tree Gelbman: Oh, my God. I died in my sleep.

Lori Spengler: What?

[Tree turns to face Lori]

Tree Gelbman: You killed me.

Lori Spengler: What?

Tree Gelbman: You poisoned it. But I never ate it before.

[a flasback: Tree drops the cupcake on the floor without eating it]

Tree Gelbman: So you had to find another way. Then Tombs fell right into your lap. Perfect scapegoat.

[flashbacks: Tombs is transported on a stretcher while Lori watches; Lori injects Tombs sedatives; Lori plants a knife in Tombs' room and covers his face with the babyface mask; Lori kills Tree, then removes the mask]

Tree Gelbman: You had access to him. Did you drug him first? You knew that if he escaped, everyone would assume that he killed me. But it was always you.

Lori Spengler: [chuckles nervously] Tree, are... is this a joke? You think I would actually try to poison you with a freaking cupcake?

Tree Gelbman: [shrugs] Okay then. Prove it.

[Tree takes the cupcake, blows the candle and hands the cupcake back to Lori]

Tree Gelbman: Go on, Lori. Take a bite. Go on, Lori.

Lori Spengler: [shakes her head, chuckling nervously] You really are crazy.

Tree Gelbman: [smiles] Okay then. I'll take it down to the police. I'm sure they can tell us what your little birthday treat is made of.

[as Tree starts walking away, Lori wears a sinister expression. She grabs Tree's hair, then knocks her against the bathroom door. Tree falls to the floor. While she is momentarily stunned, Lori chuckles nastily, locks the room door and faces Tree]

Lori Spengler: [contemptuously] You stupid little whore.

Tree Gelbman: [fearfully] I know I've been a bad roommate, but... isn't this a bit much? What the hell?

Lori Spengler: Oh, I don't know. Maybe because you wouldn't stop sleeping with him.

Tree Gelbman: What? Gregory?

Lori Spengler: [venomously] But he just kept choosing you over me. I guess all he wanted was a cheap slut like you!

Tree Gelbman: [in disbelief] Wait, you've been killing me over some stupid guy?

Lori Spengler: [shakes her head] Oh, that's not the only reason. You're a dumb bitch, too! What I really wanna know is, how did you figure it out?

Tree Gelbman: Because you've killed me before.

Lori Spengler: [smiles] Then I guess I'm just gonna have to do it again.

[Lori steps toward Tree. Tree kicks her in the stomach. Lori doubles up painfully]