Contains a parody of the Maxell "Blown Away Guy" ad - we see Walter Bishop 'relaxing' in front of a huge bank of speakers, sitting deep in an armchair, while playing classical music at high volumes.
An observer can be seen at end of the hospital corridor in which Olivia and Broyles are walking at the end of the episode.
The glyphs for this episode spell out: LIMBUS
The white figurine on the office desk in the green universe is seen on the shelf in the house in the red universe.
At the gas station, when Noreen Miller is filling up, the emblem on the front of her Dodge mini van is obscured with silver tape. There is also a Ford Explorer, which leaves the station as the scene opens, which also has its grill emblem covered with silver tape.