Mattel would not allow the first film to have a Barbie doll because they didn't want Barbie to be seen with a definitive personality. The writers reworked it so that way a Little Bo Peep figurine would be the love interest instead. However, after the huge success of the first one, Mattel allowed her to appear in the sequels.
Not that her personality is very deep — all the Barbies featured seem to be pretty ditzy.
Though the Barbie featured in Toy Story 3 ultimately turns out to be very moral, brave and resourceful, once she realizes her friends are being abused. And much smarter than she acts — she comments at one point about the nature of political power stemming from the consent of the governed. In those words.
Then-Disney exec Jeffrey Katzenberg wanted Toy Story to be "edgy", which resulted in more adult humor and a Jerkass version of Woody. A story reel version was shown to Roy Disney, on what has been dubbed by the production team "Black Friday", who called it "one of the worst things I've ever seen." The Pixar boys started from scratch and the rest is history. Not to mention that Toy Story production was almost completely canceled as a result of Katzenberg getting exactly what he asked for and not liking it. Legend has it that Pixar intentionally made the reel obnoxiously bad in hopes of changing the execs' minds. It worked almost too well; Disney almost killed the movie outright, and it took a drastically revised script to convince them to give it a second chance. Here's a video describing the ordeal.
In the first film, the "Strange Things" montage was not originally planned. Woody's world was going to change more gradually over a few scenes. Then Tom Schumacher, a VP at Disney, suggested it be done in a montage, to which John Lasseter thought, "Ding! I could have had a V8!" and put a montage in.
Bo Peep is voiced by Annie Potts, best known for playing Janine Melnitz (which is very jarring to see as Janine Melnitz is not as sweet and caring as Bo Peep — and, if you follow the cartoons, the guy Janine is in love with is more interested in paranormal science than women) on the live-action movie version of Ghostbusters, or the wacky record store owner in Pretty in Pink.
Don't forget that she was also fairly well known for her role on Designing Women.
British viewers who grew up during The Nineties should recognise TV presenter Andi Peters as Male Package Handler 1 in the second film. ("Hold it! There's a couple more bags coming from the terminal!")
In Sweden, Andy was Cody and D.J. in the first film; in both sequels, he was another Total Drama contestant: Duncan!
Real Life Writes the Plot: A primary reason the developers decided to make the movie about toys in the first place was due to the limits of mid-90s CGI. Since the technology made everything look plastic, they decided to have the characters be made of plastic.
What Could Have Been: Probably a good thing this didn't happen. Part 2 was originally meant as a low-budget straight to video release, as per usual of Disney at the time. However, the Pixar leadership decided not to sully their studio's reputation by releasing an inferior movie, then petitioned to make it a full-featured theatrical release instead.
The original Toy Story 3 developed by Circle 7, which was about Buzz getting shipped to Taiwan due to a massive recall, and his friends having to go save him.
There's also a script floating around the Internet for a Toy Story 3 that would have focused on Woody and some of the toys being stored in Andy's grandmother's house rather than sent to a daycare center (and the characters who weren't in the third movie would have been in this one, like Bo Peep and Lenny the wind-up binoculars).
What Could Have Been: In the original treatment Woody was a Jerkass and intentionally threw Buzz out the window, and the other toys threw Woody out the window after he insulted them all.
That treatment was written deliberately over the top because of repeated Executive Meddling demanding Woody to be less kid friendly and more of a jerk. Pixar was secretly hoping the Disney execs would be so horrified with Woody’s unlikable character that they would order them to rewrite the film as they pleased. Fortunately, this is exactly what happened.
In the topic about dubs, in the Japanese version, Koichi Yamadera and Tessho Genda were considered to voice both Woody and Buzz respectively. Instead, they were voiced by the Japanese comedians Toshiaki Karazawa and George Tokoro respectively. This becomes being ironic since Mr. Genda voiced Zurg in the Buzz Lightyear: Star Command animated series, who is Buzz's sworn enemy.
Bill Murray, Jim Carrey, and Billy Crystal were all considered for the role of Buzz Lightyear. Crystal turned down the part and regretted it so much he jumped at the chance to do Monsters, Inc. when Pixar came calling again.
Originally, a Barbie doll in a Pimped-Out Dress who acted like Sarah Connor from the Terminator movies was supposed to have been Woody's love interest after she rescued him and Sid's mutant toys from Scud the dog. Mattel refused to give Pixar the rights to use Barbie (fearing that the movie wouldn't be successful and sales of Barbie dolls would plummet because of the movie's supposed failure), so Woody's love interest was changed to the Little Bo Peep figurine and Woody hatched a plan with Sid's mutant toys to trick Scud the dog during the escape to the backyard. It wasn't until the first Toy Story became popular enough for a big-screen sequel (and a third installment) that Mattel decided to let Pixar use Barbie as a character.