Easter eggs (Inquisition)

Video Games

A ladder can be found, and "Can I get you a ladder to get off my back?" is scratched into it. This is what a violent Warden sometimes says when chosen or told to perform commands.
If you tell the soldier outside of Redcliffe that you are with the Inquisition, she will reply, "Sure, and I'm the Empress of Orlais." Similarly, when at Lake Calenhad Docks in Origins, if you tell Carroll, who is guarding the ferry, that you are a Warden, he will reply, "Sure, and I'm the Queen of Antiva."
When speaking with the Bull's Chargers, Stitches will retort to Iron Bull's comment about how his healing potions taste like crap with "That's because it's a poultice, sir - you're not supposed to drink it."

During Promise of Destruction in the Castle of Caer Oswin, in the corridor where you meet Cassandra's apprentice, go to the eastern end of the hall, and there is a krogan head mounted on a wall.

a krogan head mounted on a wall

In the Multiplayer Map: Orelisian Chateau there is a trophy room. Mounted above two animals on a wall is a krogan head.

Cole makes several quotes referencing other media, one of which is, "He teaches them to fight with a secret flaw, part of a glorious strategy." This was said by Master Li in Jade Empire.

There is a codex entry titled "Plants vs. Corpses", an obvious nod to the game.
In Crestwood, on Linden Farm, a row of giant flowers can be found against a wall, each in their own column. In several of the columns, corpses can be found on the ground.

When on the Storm Coast, a dragon can be found battling a giant. If Varric and Cassandra are in the party, Varric will say, "Seeker, you're the dragon expert, what do we do?" This is potentially a reference to when Cassandra defeats a dragon in the movie.

At Skyhold, you can manage to fall through the floor and appear in a cavernous room with creepy music discovered under Skyhold houses. In it is what appears to be a pie in a top hat. Graham Kelly, a BioWare environment artist, calls this "The Lord of the Pies".
In the Western Approach, a floating, golden chalice can be found.