- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
An anomaly of subspace for warp-traveling vessels, as when one mass was snagged by the U.S.S. Mekong and clogged up its starboard nacelle, creating instability in the warp field and leading to a shut-down.