Chrono Trigger Prerelease
The Epoch is fully operational in the Chrono Trigger Prerelease. An alternate version exists -- it seems to be a hovercraft, only capable of traveling across land and over forests and mountains. It is logical to conclude that the Epoch was intended to move across land rather than be stationary at first; its warp animation is a simple fade to white. The graphics for this Epoch ARE in the FINAL version of Chrono Trigger, but the coding is not; the stationary Epoch takes its spot. It was most likely changed due to the fact that if the player warped into a time period in which forest, mountains, or other impassable objects sat at the spot of the warp, the player would awkwardly be forced to return to the original era.
Developers could obtain the Epoch at any time by using a debug object in the upper left of the Millennial Fair. Activating it would display the message "Time Machine Get", and it would appear on the 1000 A.D. overworld.
You can see the hover Epoch in action at http://www.youtube.com/watch?v=8d_zWnhQO7w.
Moving pictures thanks to RyogaMasaki.