Clara is making her way closer to Doc during the following.
Doc: (to Clara) You're doing fine! Nice and steady! Come on! Just a little further!
Clara: I can't Emmett, I'm scared!
Marty: (w.t): 70!
Cut back to Doc and Clara.
Doc: Come on...you're doing fine...nice and easy...that's it...don't look down...
Marty: (w.t) Doc! The red log's about to blow!
Doc: Clara!
Another explosion. Clara nearly falls of the train, but her dress catches on something and she's hanging upside down.
Doc: Whoa!!
Clara: Emmett!
Doc: Clara! Hold on!
Clara: I can't!
Clara's dress is ripping and she's getting closer to the ground. Inside the DeLorean, Marty notices the hoverboard.
Marty: (w.t) Doc! I'm gonna slip you the hoverboard!
Doc: Marty! Watch out!
Marty sees a sign saying that the track is not finished yet. He ducks and the car smashes through the sign, missing Marty's head though.
Marty: Argh!
Clara: Ahh!! Ahh! Emmett, help!
Doc: Hold on, Clara! Whoo!
We see the end of the bridge, and the train heading towards it. There isn't much time left! Cut back to Marty and Doc.
Marty: (w.t) Doc! Catch it!
Marty sends the hoverboard flying toward Doc. Doc manages to "catch" it with his feet.
Doc: Whoa!
Marty: Yes! Yes!
Clara: Emmett!
Doc: Hold on!
Clara's dress rips and she falls.
Doc: Woah!
He picks her up just in time, and they fly off on the hoverboard.