[Clara has pulled the train's whistle, causing Doc to look back towards the cab]
Clara Clayton: [Waves] Emmett!
Doc: Clara!
Clara Clayton: I love you!
Marty McFly: [Into walkie talkie] Doc! Doc, what's happening?
Doc: [Into walkie talkie] It's Clara, she's on the train!
Marty McFly: [to himself] Clara? Perfect.
Doc: [Into walkie talkie] She's in the cab; I'm gonna go back for her!
Marty McFly: [Into walkie talkie] The windmill! Doc! The windwill, we're goin' past fifty, you'll never make it!
Doc: [Into walkie talkie] Then we'll have to take her back with us, but keep calling out the speed!