The first shot we see of the actual game is a plaque with figures of Solaire and the text "Praise the Patreons".
Kingseeker Frampt and Darkstalker Kaathe are on the ambulance.
The sarcophagus which kills Iudex Gundyr contains the Mask of the Father.
A bus sign in the Undead Settlement points to Hemwick.
A Cleric Beast can be seen and heard screaming in the background underneath a Paleblood Moon.
There's a picture of Vendrick in Anor Londo.
Matt finds a rusty coin.
Sirrus of the Sunless Realms is in the background sunning her self in the Firelink Shrine when the Fire Keeper asks Matt to touch her left boob.
One of the weapons Matt accidentally throws into the Ancient Wyvern's head is the Saw Cleaver from Bloodborne.
Crossbreed Priscilla can be seen waving from one of the towers in Anor Londo, most likely the one where the Ashen One can meet Company Captain Yorshka.
The Anor Londo travel guide has a picture of a Crow with the text Lordran Airways.
Consumed King Oceiros has (poorly) taped a picture of himself to a picture of Seath.
The Infant Great One from Bloodborne lies on the ground in the kiln.
The first message Matt finds in game is written in elvish.
At one point, Matt's helmet transforms into Mega Man's.
The ambulance driver gives Matt a package of mentos.
The Fire Keeper claims to have been a character in Dead or Alive before taking this job.