Image ©2012 Disney/Pixar. All Rights Reserved.

The lovable but naïve Rex the dino stars in Pixar's latest "Toy Story Toon," Partysaurus Rex (playing in front of Finding Nemo 3D on Sept. 14). It's bath time for Bonnie's toys, and Rex goes from party pooper to party animal when he's recruited to take charge. So naturally mayhem ensues when the bathroom overflows with the sudsy fun. Pixar vet Mark Walsh directs his first short, which was animated at Pixar Canada in Vancouver.

"When I was a kid I loved bath time," Walsh admits. "It was like being in a giant hot tub with foam and your own toys. And when I went to high school I wanted to reinvent myself as someone hipper and cooler, which lasted about a week or two. Rex is so sweet and sincere. He wants to get along with everybody and seemed like the perfect guy to want to reinvent himself. Wallace [Shawn] is so smart but he's the first to admit that he's not hip to the Rave culture. That's why he was so perfect when Rex says, 'I can get this party started up.' Rex is smart but just naïve enough to get into unfortunate situations."

Pixar works on story, art, and editorial in Emeryville.  We work on story, art, and editorial, and our director, editor and production, while Canada takes the shots through production, layout, animation, lighting simulation, and effects. Then they get the movie back in Emeryville and post it, doing all the sound mix and color correction, and then they finish it back up there.

"So it's a young company and it's like an outpost for the Pixar culture," Walsh explained. "They're smaller and more agile, and everybody there is really young. I think it has the feel and energy of a young company combined with the culture that has worked so well for Pixar here. There was one animator up at Pixar Canada who had a scene with Rex. This animator was really into puppets. In his office he's got different puppets that he's made. And during one of our teleconference meetings where it was his turn to present, they panned–up/over and he wasn't there. It was just his puppet. He was hiding under the table.

"I think they were a bit afraid when they first saw this project because it was going to be bigger than anything they've ever tackled," Walsh adds. "But it was a defining moment for that studio. They pushed themselves beyond what they thought they could do."

Partysaurus Rex director Mark Walsh. Image © 2012 Jessica Brandi Lifland. Courtesy of Disney/Pixar.

But with 174 difficult shots, this fast and furious short needed some extra tech help from Emerville. "Suds were the big challenge," he continues. 'Can I get the suds to be really high?' 'Oh, that's so difficult.' For a foam party, you've got to have them. And I was waiting to get my hopes dashed when they showed me the shot of the showerhead coming on and blasting all these soap suds into the air. And everyone in the room was amazed at how emotional I got. The tech people in Emeryville worked with the Vancouver studio. It's similar to the Cars 2 simulator but if the bubbles aren't the right variation it starts to look like caviar."

Of course, Shawn shined as Rex, since he knows his character so well and enjoyed the spotlight. Walsh says it really is him in the short: his attitude and trying so hard to step outside himself and be more effusive - to be the life of the party. Walsh likes to recall how John Lasseter first approached Shawn at a one man show in LA with a toy dinosaur in hand and asked him to play that in Toy Story. Shawn wasn't quite sure what to make of the proposal and Walsh thinks he's still a bit mystified by the phenomenal success of Toy Story.