The Romulans were experimenting with a molecular phase inverter to create an interphase cloak. This is similar to what the USS Pegasus illegally attempted to test in "The Pegasus". Geordi ominously foreshadows this in his penultimate sentence: "Well, maybe we should develop our own interphase device."
Thomas Kopache is one of only a few actors to appear on all four of the Star Trek TV spin-off series and is one of only five actors to play seven or more different characters in Star Trek (the others being Jeffrey Combs, Randy Oglesby, J. G.Hertzler, and Vaughn Armstrong).
Thomas Kopache has played Mirok in TNG "The Next Phase", Train Engineer in TNG "Emergence", Enterprise-B communications officer in Star Trek Generations, Viorsa in Voyager "The Thaw", Kira Taban in DS9 "Ties of Blood and Water" and "Wrongs Darker Than Death or Night", Tos in Enterprise "Broken Bow" and a Sphere Builder test subject in Enterprise "Harbinger".
Susanna Thompson has played four characters in the Star Trek franchise, the Borg Queen in Voyager episodes "Dark Frontier", "Unimatrix Zero", and "Unimatrix Zero, Part II", Lenara Kahn in DS9 "Rejoined", Varel on TNG "The Next Phase" and Jaya on TNG "Frame of Mind".