- Marty: "What does this mean, 'Point of No Return'?"
- Doc: "That's our failsafe point. Up until there, we still have enough time to stop the locomotive before it plunges into the ravine. But once we pass this windmill, it's the future or bust."
- — Marty and Doc discuss elements of his demonstration model in 1885, Wav
Up to this spot, where a windmill stood, there was still time to stop Locomotive 131, which was pushing the DeLorean time machine along the railroad tracks, before it went off the edge of Shonash Ravine. But once past this point, "it's the future or bust", to quote Doc.