Fringe Connections

Olivia saw Brandon as a zombie in her mind in "Lysergic Acid Diethylamide" because he wanted to cut out and study her brain in "Entrada".

William Bell left Massive Dynamic to Walter.

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

Walter looked upset when he found Peter's coin in the lake house in "There's More Than One of Everything" because Peter was holding it as he died in "Peter".

Olivia pulled up a list of the frozen heads found in S02E04 'Momentum Deferred' and they were all marked with "2E204", a reference to the episode in which they were stolen.

A frog can be seen on the dock when Walter is high.

The entire story of Fringe started in "Peter" when Walter crossed worlds with a boy that wasn't his because he couldn't stand to let Peter die, and the entire story concluded in "An Enemy of Fate" when Walter crossed worlds with a boy that wasn't his knowing that by doing so he would never see Peter again.

When Nina looks in Bell's storage room for his copy of the First People book the camera pans by a copy of 'Dr. Spock's Baby and Childcare'.

A butterfly can be seen on a lampshade near the front of Olivia's apartment.

The bus in "The Ghost Network" is ambered. Ambering later becomes a real safety tool used by the other side as seen in "Over There (Part 1)".

Donald helped Walter set up the pocket universe hiding spot.

Butterflies can be seen in Etta's apartment.

In "And Those We've Left Behind" Peter picked up the same toy plane (perhaps not literally the same) that he played with in "Subject 13".

Sam Weiss died 10-15 years earlier in a shootout with Observers trying to protect the radio signal relay used to locate Michael.

Butterflies can be seen in Olivia's bedroom.

Olivia's pregnancy dream in "The Same Old Story" is in a waiting area with giant tulips.

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

The butterfly glyph can be seen on the wall in the diner where Olivia and Lincoln meet.

September's device in "A Short Story About Love" led Peter to the beacon from "The Arrival".

This episode reveals that there is more than one Observer. The intro sequence since the pilot episode has had a single frame that says "OBSERVERS ARE HERE".

A leaf can be seen on the bio-scan monitor at the Liberty Island security checkpoint.

Olivia shot her captors in "The Human Kind" with the bullet she took from Etta in "The Bullet that Saved the World".

The crane that crashed during the intro has a Massive Dynamic logo on it.

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