*The train at the beginning of the film features the number 95 which is of course Lightning McQueen's number from Cars (2006), which in turn is a reference to the year when the original Toy Story (1995) was released.
*Andy's room features a number of in-jokes:
A poster on his wall of an Aston Martin, the same model as Finn McMissile from Cars 2 (2011) and a flag for Pixar University...
...a bunch of door stickers including Crush from Finding Nemo (2003), a Newt Crossing sign in reference to the cancelled Pixar production Newt and the 'M' logo from Monsters Inc, (2001)...
...a sign above the door reads W. Cutting, in reference to the Boulevard where Pixar was originally located...
...the pins on the map indicate the hometowns of the production crew...
...a Nemo sticker on the side of Andy's toy chest...
...and finally, the letter on Andy's pin board is addressed to Emeryville where Pixar Studios is based.
*Andy's sister is reading a magazine with a picture of Darla from Finding Nemo on the front.
*The garbage man is clearly Sid, the antagonist from the first film.
*The car licence plate is once again A113.
*A toy version of Mr. Ray from Finding Nemo is on the shelf at Sunnyside Daycare.
*During the tour of Sunnyside, a lego model can be spotted which is almost identical to one used in Toy Story 2 (1999).
*When Woody hangs in mid air following his escape from Sunnyside, a collage can be seen in the background. One of the designs depicted therein is of the famous Luxo ball.
*Bonnie places Woody in her backpack, the front of which features Wally from The Adventures of Andre and Wally B. (1985).
*When the toys at the daycare centre go into hiding in anticipation of the kids' arrival, we see the same toys that hid from an over zealous child many years before in Tin Toy (1986).
*The child in the glasses is wearing a t-shirt bearing Lightning McQueen's '95' insignia.
*Tin Toy is referenced a second time when the lead character appears on the front cover of a storybook.
*A simplified wooden toy version of Lightning McQueen can be seen in the background.
*Among the many items being bartered in Sunnyside are some batteries which are made by the fictional company 'Revolting', first seen as a sponsor in Cars.
*The vehicle that Lotso and Chuckles ride on is a Pizza Planet truck.
*When Woody returns to Sunnyside, the name 'Atta' can be seen on the wall which is a reference to Princess Atta from A Bug's Life (1998).
*The batteries in Buzz's back are made by Buy N' Large (BNL), the fictional corporation from Wall-E (2008).
*This one appears only in the trailer. A postcard on Andy's pinboard is from Carl and Ellie Fredricksen from Up (2009).
And now for the others. Each of these appear at Sunnyside:
*Many claim that the fire-truck depicted below is a toy version of Red from Cars. Owing to the number of Cars references already in the film this isn't unlikely; however, there are many differences and considering that Red is designed after a real-life fire truck, it's entirely possible that this toy is as well. The same can be said for the tractor which bares as many similarities to its real-life counterpart as the anthropomorphised version in Cars.
*One of the toys appears to be a loose amalgamation of Mike and Sulley from Monsters Inc,.
*The blue toy which hops under the bucket looks slightly like Flik from A Bug's Life, albeit a short and fatter model.