Temporal rift

A temporal rift is a tear in spacetime and an extremely dangerous temporal anomaly. Encounters with temporal rifts usually end with the vessel making contact with the rift being transported to a different time and space.

In 2278, the USS Bozeman (NCC-1941) entered a temporal disturbance in the Typhon Expanse, travelling to the year 2368 to collide with the USS Enterprise (NCC-1701-D), starting a temporal causality loop. 

The USS Intrepid, under the command of Luciano Mantovanni, fell through a temporal rift, re-emerging in 2368. (Star Trek: Liberty)

In 2366, the Enterprise-D also encountered another temporal rift near Archer IV. Sensors indicated an emerging vessel, but the readings vanished and the phenomenon collapsed shortly thereafter. In actually, the rift was created by a battle between the Romulans and the USS Enterprise''-C in 2344 at the Narendra system. The Enterprise-C emerged from the rift, creating an alternate timeline in which the Federation and Klingons were still at war. The rift was collapsed by sending the Enterprise-C back through, restoring the timeline.''

29th century Starfleet vessels could travel through time by creating artificial temporal rifts. One such ship, the Aeon did this to travel to 2373 in an attempt to destroy the USS Voyager (NCC-74656). The rift destabilised, sending both Voyager and the Aeon back to the 20th century. 

Also in 2373, a Cantabrian away team, aboard a shuttlecraft, was hit by a temporal displacement wave (which, in turn, created a temporal rift), travelling back in time. After gaining assistance from Cantabrian (NCC-607) captain Thekla Lawless, the team found the temporal wave and returned to their own time. (: "The Fire In Which We Burn")

Gordan's vessel exploded in 2376 after an encounter with a temporal rift. (: "Occurrence, Part II")

In an alternate timeline's year 2404, Admiral Kathryn Janeway created a temporal rift to help Voyager'' return home 16 years earlier than in her timeline. The plan worked, with Voyager returning from the Delta Quadrant in 2378 instead of 2394 in the original timeline.'' (