The trivia items below may give away important plot points.
Olivia, now "possessed" by William Bell (played by Leonard Nimoy) repeatedly lifts her right eyebrow in the manner of Nimoy's Star Trek character Mister Spock always did. This can be seen in OS (#3.16), Stowaway (#3.17) and Lysergic Acid Diethylamide (#3.19).
Koenig, the thief who is shot and killed at the beginning of the episode, was presumably named after Walter Koenig, who co-starred (as Ensign Pavel Chekov) with recurring Fringe cast member Leonard Nimoy on the original Star Trek television series.
The antagonist in this episode is definitely a scientist in both universes. In the RED universe in "Immorality" (S3, episode 13) the names "Watson and Krick" are referred to as "those DNA guys" - as if in historical reference to his name. Sadly, in the BLUE universe, Dr. Krick was the scientist that turned to experimenting on other humans to better his own son.