"We were using PBR (physically-based rendering), which can be very computationally expensive, so our biggest concern in starting this was render time," Chen adds. "So we had to work out the technical solutions and educate our artists to work in very efficient manners to get the final images out. By the end, we worked it out to achieve multiple iterations."

Most of the characters were designed by Peter de Seve (Ice Age), but Hill was not satisfied with the way the lead bunnies looked with fur: E.B. (voiced by Russell Brand) and Dad (voiced by Hugh Laurie). "We reworked it and made them look more sleek and smooth and not as gray or modeled or scruffy as some of the original artwork had indicated," Chen explains.

Overall, the rabbits were straightforward, including the ninja bunnies known as the Pink Berets. However, E.B.'s interaction with Fred was different from his interaction with his fellow CG buddies.

"A rabbit is more comfortable on all fours, but E.B., for the most part, is walking and talking and performing like a human, so the challenge is to make his performance look enough like an animal that's standing up on two legs and not a guy in a suit," remarks Andy Arnett, Rhythm & Hues' animation director. "The other challenge is to get the age appropriateness of the character. We wanted him to look like a teenager and not a little kid, which is tough when you're working with a character that's 22 inches tall and looks like a little kid. So it was important to have him standing and walking and behaving like a teenager. We still had moments where he would run on all fours or hop up onto a countertop, so we would switch back and forth. The hero characters also had extremely long feet like Bugs Bunny, so it was tricky maintaining their animal-like movement.

But the biggest problem was getting the performance of E.B. just right, which, unlike other talking animal movies, occurred as they went along. "There was a concern early on not to make him come across as too cynical or too irritating," Arnett continues. "They wanted him to be appealing in his desire to be a drummer rather than the Easter Bunny. We were careful to incorporate that because when you're using Russell Brand as a starting point, it's easy to become snarky in the performance. And his interactions with Fred changed as well. Early on they were more antagonistic toward each other and E.B. was more of an irritant to Fred, but as it developed they became buddies. That colored the performances to make E.B. more supportive as well."

Then there was the whole drumming challenge, which is E.B.'s defining characteristic. "We had to figure out how to make that work with a rabbit so we did an early test and had a lot of fun with it," Arnett suggests. "We went over the top and it went over really well, but when it came time to do our first teaser, different ideas had developed from the test. It went from being like a little kid drumming to being more like a professional musician who was very cool and comfortable. So we had to come up with different styles of a rock drummer. That required digging up lots of reference and finding a groove for E.B. that we could apply to all these other scenes. We looked at Neil Peart from Rush. We also found a YouTube clip of a little kid drumming, so we took a lot from that piece of reference and incorporated it into the later sequences."

It's a far cry from Alvin, Yogi or Garfield.

Bill Desowitz is senior editor of AWN & VFXWorld.