In this episode, Walter and Olivia continue their quest to retrieve Peter while Bell intercedes and helps them with their mission. In an action-packed climax, Olivia is kidnapped and Fauxlivia takes her place for the return trip home, leaving Olivia stranded in the alternate universe.
This episode's glyphs spell:
A chalkboard in Walternate's old Harvard lab in the Redverse said "A demon's twist rusts", which is an anagram for "Don't trust Sam Weiss", hinting at Sam Weiss's significance to the unfolding plot.
The Observer can be seen walking behind Olivia, Walter, and William Bell as they're eating fast food.
This mirrors what Charlie said to Olivia earlier.
William Bell provided all of the energy in his body to fuel a universe hop for Walter, Peter, and Fauxlivia in "Over There (Part 2)". (Image 1)
He suffered some of those consequences in "Over There (Part 2)".
William Bell was unwell and needed oxygen in Olivia's memories in "Momentum Deferred" which could be because of how many times he crossed over. (Image 1)
In "Bloodline" a pregnant Fauxlivia worried that she was a carrier for VPE, the same disorder that led to her sister's death.
In "The Day We Died" Peter used the Machine to rip holes in both universes and bridge them together.
Michael's disappearance in the future was a mystery, like Peter's disappearance in the Redverse.