When the manager of the hotel is shipping Woody off to the highest bidder, the address on the shipping label is Al's Toy Barn. This may reference Al the toy collector from Toy Story 2, who stole Woody because he is a very rare toy and intended to sell him as part of a valuable collection to a toy museum in Japan, evident by Woody's final bid reaching $2000.00.
The first Toy Story film of any kind (feature film or short film) that did not include John Ratzenberger as Hammy the Pig. Director Angus MacLane explained that this was because Bonnie had limited room for toys in her backpack and, "Who takes a piggy bank on a vacation?"
In the graveyard scene in the opening sequence, Betsy falls against a tombstone with the inscription, ""RIP Simon J. Palladino - A public servant with a unique vision." Simon J. Palladino was the secret identity of Gazerbeam, a superhero with laser vision, in The Incredibles (2004).
Carl Weathers provides the voice of Combat Carl/Combat Carl Jr. Combat Carl is modeled after Carl Weathers's character from Predator (1987), and also after his character, Chubbs, from Happy Gilmore (1996), who was also missing his right hand.
When Ron puts the sticker on the box Woody is in, not only was he shipping it to Al from Toy Story 2 (1999), but if you look really closely at it, you can see it says "1195", a reference to what it said on a cereal box in A Bug's Life (1998), and referencing to when the first Toy Story came out in November 95.
The line "over here" said by Combat Carl (Carl Weathers) to Jessie (Joan Cusack) in the hotel bathroom is a direct reference to the movie Predator. As this is what Mac (Bill Duke) says to Dillon (Carl Weathers) before killing the scorpion that climbs on his back.