The explosion seen after Steed throws the gavel is reused from Have Guns - Will Haggle (1968) when the ammunition shed blew up.
The door to Mother's underwater headquarters was also used on the butter churning machine in "False Witness" several weeks before.
At 42.17 Tara confronts Steed by a large brick bridge. This is the same bridge that Tara runs over in the title sequence.
Note when Tara climbs from the river after a visit to Mother's submarine lair .. An obvious double, even when entering the waiting car.
The plot is the same as The Outer Limits, Season 1, "The Hundred Days of the Dragon" by using a mask to change someone's face.