Fringe Connections

The radioactive isotope compound from "The Cure" that caused heads to explode was used as a weapon against the Observers in "An Enemy of Fate".

One of the envelopes Peter sorted through said "Thank you for your support!", a direct message from the creators of Fringe to all the fans.

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

The universe window from "Peter" was seen in Walter's storage vault in "The Bullet that Saved the World".

Walter's pose as he listens to the Mozart Requiem is a reference to the iconic Maxell tape advertisement from the '80s.

The butterfly glyph can be seen near Lincoln in the rail yard.

Peter flipped a coin through his fingers in "Safe" like both Peters did when they were near death in bed in "Peter".

Madison Square Garden in the Redverse is quarantined in amber.

The butterfly glyph can be seen as Olivia and Shapeshifter Charlie fight in the alley.

The super-sized cold virus from "Bound" was used as a weapon against the Observers in "An Enemy of Fate".

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".

The seahorse glyph can be seen on the back of one of Markham's books.

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".

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

A seahorse can be seen on Peter's luggage.

In "And Those We've Left Behind" Astrid used the same wand to detect abnormalities that Lincoln used in the opera house in "Over There (Part 1)".

Bell stole Walter's David Bowie album 'The Man Who Sold the World', which describes what Bell did multiple times for his own benefit.

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

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

Donald entered the mine 5 weeks after the invasion and took some rocks. He was described as being in his late 30s, medium height, dark hair. Donald said he was waiting for "a colleague, a scientist from Boston, to meet him." Observers found him and took him away.

The leaf glyph can be seen as Olivia and Shapeshifter Charlie fight in the alley.

Olivia's therapist in "Nothing as it Seems" is the same one she had when she was trapped on the other side in "Olivia".

Olivia entered "Martin Luther King/Eldridge Cleaver Memorial Park" which has a plaque quoting them as saying "We have a dream" rather than "I".

The hand glyph can be seen on the piano stool in the Orpheum Theater in the Redverse.