Anachronistic event

An anachronistic event is the term applied to a sequence of events that are out of sync with the normal flow of space time. In effect the event takes place in a different timeline.

Starfleet has encountered numerous anachronistic events during the 22nd, 23rd and 24th centuries, although the crews involved often have no knowledge of the events.

Star Trek: The Original Series

 * "The City on the Edge of Forever"
 * The Entropy Effect
 * The Janus Gate trilogy

Star Trek: The Next Generation

 * "Time Squared"
 * "Yesterday's Enterprise"
 * "All Good Things..."
 * Engines of Destiny

Star Trek: Deep Space Nine

 * "Children of Time"

Star Trek: Voyager

 * "Year of Hell, Part I"
 * "Year of Hell, Part II"

Star Trek: Enterprise

 * "E2"