Several costumes from this episode were later sold off at the It's A Wrap! sale and auction on eBay including the costumes of Brent Spiner, William Lithgow, Fionnula Flanagan, Jonathan Paley, and Christine Anne Baur.
As Geordi and Dr. Crusher are examining Julianna, Geordi remarks that "she age[s] in appearance like Data". This is the first mention of Data's physical appearance being able to age, and was likely included as a means of explaining why Brent Spiner looked considerably older in Data makeup by the 7th season.
Dr. Juliana Tainer (Data's mother) states that there were 3 prototypes that preceded Lore, making Data the 5th android created by Dr. Soong. It can be assumed that one of these prototypes was the "B-4" of Star Trek: Nemesis (2002).
In "Heart of Glory" (1988), it is shown that through his VISOR, Geordi can see some sort of halo or aura around Data; the explanation given is because "he's an Android". While at that point he'd not yet seen another android to confirm that hypothesis, and it's never discussed whether he sees one around Lore or not, it can be assumed that the advanced technology in Julianna also causes the android "halo" to not be visible. Otherwise Geordi could have told Data early on that his mother was also a Soong android.