The toolbox that Buzz Lightyear (Tim Allen) pushes off the milk crate has the name Binford on it. Binford was the company Tim Allen worked for on Home Improvement.
When Sid's dog is shaking Buzz in his mouth towards the end of the movie he throws him under a red car. The car's licence plate reads "HTT1195". The "HTT" stands for "Hi Tech Tunes". The "1195" stands for the date the film was released, November 1995.
There are many references made in the titles of books in Andy's room. Here are a few:
Red's Dream and Knick Knack - previous Pixar film.
Tin Toy - the first computer generated movie.
Adventures of Andre and Wally B - an animated short by Lucasfilm.
John Lasseter's name appears on a book, he is the director of Toy Story.
When Woody and Buzz are in Sid's backback there is writing which says "Julie Macbarfle has cooties!" This is a reference to a camera manager named Julie MacDonald, who was begging to get her name in the movie.
The name of the realty company that sells Andy's house is called "Virtual Realty". The movie was made using virtual reality.