Frozen Ever After features some of the puffin animatronics from Maelstrom at the end of the ride. They are located in the former oil rig scene on the right.
The cash register in Mission Space features the Horizons logo.
The Seas With Nemo features The Living Seas logo on the entrance to the conference center.
Test Track features a sign during the outdoor section that says "FN2BFRE". The World of Motion logo can also be seen throughout the pavilion.
The Buzz Lightyear Space Ranger Spin sign is repurposed from Delta Dreamflight.
Ellen's Energy Adventure mentioned "Energy: You Make The World Go Round" in the final Jeopardy scene.
The original JII music plays in the Imagination bathrooms and "Dean Finder" has a door in the current Imagination attraction.
7DMT features animatronics from Snow White's Scary Adventures.
The tree in front of Pooh is reused from a Pooh playground that was located where 7DMT is now.
Dreamfinder's flying machine can be seen in MouseGear.
The planter in front of Mission Space was formerly used for the Horizons signage.
Although it's still open, the father and daughter from CoP are featured in Spaceship Earth.
Most of the ones I know are from EPCOT, but I'm sure there are plenty more that I forgot about.