Fringe Connections

The child needed an air degradation unit in "Through the Looking Glass and What Walter Found There" because he needed a less oxygen-rich environment like where he was found underground in "Inner Child".

All of the people in Olivia's mind wear blacks and greys because Cortexiphan subjects have a strong desire to blend in.

The leaf glyph is on the electronic keypad at Massive Dynamic.

Markham took a liking to Olivia when they met for the first time in "Ability". Decades later in "Transilience Thought Unifier Model-11" he buys her when she's stuck in amber.

Michael can show emotion as he cried when he saw Nina's dead body.

A frog can be seen in Walter's Monty Python trip.

A flashback at the end of "Grey Matters" revealed that it was William Bell who removed the pieces of Walter's brain. In "Over There (Part 2)" Bell said he removed the pieces at Walter's own request due to fears about the man he was becoming.

The yellow dot in the final glyph of the episode is replaced by a yellow heart.

The flower glyph can be seen on the wall in Karen Truss's house.

Parts of Officer Gillespie from "Fracture" were seen in Walter's storage vault in "The Bullet that Saved the World".

Marshall Bowman had a disk in his hand like John Scott and the woman in 'The Ghost Network'.

The butterfly glyph can be seen on a door in the pocket universe.

September was labeled as "Mr. X" on Walter's computer in "The End of All Things", the same name that fans used to refer to the man Peter freed in Olivia's mind in "Lysergic Acid Diethylamide".

Carr's work review sent to Astrid from his previous employer shows that in the three years prior to his dismissal, he only missed three days of work. He was out for only one day each year and each year it was the same day: Valentine's Day.

A seahorse can be seen hanging from the taxi when Walter listens to music.

The combination to Bell's safe in "Concentrate and Ask Again" was 0-5-2-0-1-0, the same combination used in "Five-Twenty-Ten".

There are 'Wanted' billboards for the Fringe team.

A hand can be seen outside the entrance to the daycare center.

Walternate has three solid-color panels on the wall of his office in "Bloodline": blue, red, and yellow. These symbolize the two universes (blue and red) and the rewritten timeline without Peter (yellow) starting from "Neither Here Nor There".

The license plate on Olivia's SUV reads 1R2D21, and the licence plate on Broyles's SUV reads 1C3PO1.

Butterflies can be seen in Olivia's bedroom.

The password to retrieve Michael in "Black Blotter", "Black Umbrella", came from the poster for Singin' in the Rain, from which September chose his new name (Donald O'Connor) in "The Boy Must Live".

Jones said there are 10 tests for Olivia in total. The first was a box of lights that Olivia had to turn off with her mind.

A hand can be seen on the wall when Olivia and Peter attack the Observers and Loyalists.