Salome Jens, the woman who portrayed the Humanoid Progenitor in Star Trek: The Next Generation (1987) The Chase (1993) (and whose picture is shown in this episode), also played the Changeling leader in Star Trek: Deep Space Nine (1993).
The Self Sealing Stem-Bolt was first introduced in Star Trek: Deep Space Nine (1993) and has been a running joke in the Star Trek Verse since. It has now been re-introduced.