Doc: Clara! Climb out here to me!
Clara Clayton: I don't know if i can!
Doc: You can do it; just don't look down!
[Clara looks down at the churning wheels and starts leaning out]
Doc: That's it!
[Clara climbs over the cab and steps her high-heeled boots onto the train's thin, precarious ledge]
Marty McFly: [Into walkie talkie] 60 miles an hour, Doc!