While the challenge with any long-running series is to find a fresh, inventive angle for every new crop of episodes, CBS's reality competition series "The Amazing Race" looks to the past this time around for its 18th cycle. Subtitled 'Unfinished Business,' previous contestants from the past 17 seasons who came close to winning their respective race but failed for whatever reason come back for another try at winning a million dollars in the always exciting race around the world.

In Sunday night's 18th season premiere, the eleven familiar teams start in Palm Springs, California but don't stay Stateside long before they're heading to other parts of the world with U-turns, Speed Bumps, difficult challenges and, of course, each other getting in the way. Series host Phil Keoghan previewed the new season earlier this week for our Jim Halterman and shared just how much of an advantage the returning teams have, if he's still surprised at what unfolds on the Race and details on the just-released documentary of his momentous 2009 bike ride across the United States to raise money and awareness for Multiple Sclerosis research.

Jim Halterman: With so many great teams over the years, how did you ever decide who would come back for this 'Unfinished Business' season?

Phil Keoghan: I think the audience picked because they really told us who they liked the most through the feedback that we got on fan pages and websites and even the people that I get asked about the most. Then we picked in terms of the stories that we felt were strongest and related to the idea of 'unfinished business.' The teams that had stories that were the most captivating when it came to teams that had u-turns, teams that got lost, teams that came very close, teams that took the wrong pee-break and teams that were harboring a lot of regrets and woulda-coulda-shoulda in their experience from being on the Race so that's really how it came about.

JH: Do you feel that these teams had much of an advantage because they'd done it before? From what I've seen so far, you still see mistakes being made, the clashing of personalities, etc...

PK: I think it's definitely an advantage to have done the Race before so that puts them on equal footing but what it does is also increase the level of competition because now you're competing against teams that are more savvy so you can't afford to slip up. You really have to be on top of it. When you've got that many teams out there who have done it before and they know how everything works you really can't afford to make any mistakes at all.

JH: Any teams from the past you wanted to get for this season but didn't?

PK: I would have loved to have had the Home Shopping team (from Season 17) come back again but they weren't available. There were lots of teams that I would have loved to have come back. I would have loved to have another 10 teams! In the end, we had to make some pretty tough choices about who's going to come back and those teams couldn't wait to come back so we were very lucky.

JH: What's different this time around? Any new twists in the game?

PK: Right out of the gate, we added a challenge that shocked them and really had consequences not just in the first leg but the following leg. That was crucial and a key moment because you're now racing with some extra baggage with you. Also, rather than add new elements we made sure to amp [the existing elements] up and challenge them more since we knew they'd done it before. The challenges were pretty taxing and we heard from the teams. Some of them made it pretty clear that they thought this race was tougher and they didn't remember it being this hard the last time they were on. I just said 'Listen, you want to come back and get a second chance we're not going to hand this out. Second chances don't come easy. If you want to be here and run against these other teams, you're going to have to work for it. This is 'The Amazing Race' and it will tax you.'

JH: I'd consider most of the returning teams as nice teams but do we see some villainous behavior come out in the course of this season?

PK: Yeah, I think that you've got a lot of great potential for that kind of behavior. Like with Ron, is he going to revert back to his old behavior when he ran the race [in Season 12] - he probably had one of the biggest personality transformations on the air ever - but is he going to revert back to his old ways now that he's in a race and under pressure? I think anytime you amp things up the way we have and you put people out on the road to race and they get closer and closer to the idea of winning the race you're definitely going to have tension and interesting strategies. As the race continues, there are a couple of teams that alienate themselves from the others because of their competitiveness and because of certain choices they made in terms of what information they wanted to share or not share so it's pretty intense and it gets more and more as the race goes on.

JH: You've been through this so many times, Phil, but were you surprised by anything you saw this season?

PK: I'm always surprised because I'm not very good at picking who's going to do well and I would venture to say pretty much everyone on the production team is the same. We're constantly surprised and I think that's one of the key ingredients for why the Race works is that the viewer never really has a chance to work out what's going to happen. It's not a predictable competition where you have a track record for a team or a particular player and you're able to anticipate who is going to do well. In this Race, the lead changed a lot, the key players changed a lot...it's definitely surprising and the eventual teams racing to the finish line at the end was an interesting mix as to how they got there. There are a lot of teams that went from right at the back to right to the front and that happened a lot. I would think 'There's no way they're going to make it now. The writing is on the wall for them' and then miraculously they'd come back fighting back again. I love that. I've never been good at predicting the race and I hope I never am. If I were ever able to pick [the winner] it would mean that something in the race wasn't working. There would be something missing if I could predict it.

JH: Do you think the ultimate winner is truly the best player or is it sometimes just a game of chance?

PK: No, I do think that every winner that we've had even back to Flo and Zack [in Season 3] when Paul was ready to give up on the last leg and then they ended up winning - I do think chance plays into it but I think in the end chance can only get you so far. The team that crosses the finish line first is absolutely the team that has been the most consistent as a team in terms of how they've tackled the navigation, the travel choices, the detour choices and how they've tackled new and interesting road blocks. Chance is absolutely a factor but ultimately you don't get to the finish line and win 'The Amazing Race' by chance.

JH: What makes a location an ideal location for this season? Is there a criteria a spot has to meet?

PK: Ultimately, the network signs off on the final route but I think it's always about where have we not been? What have we not done? What would be really interesting? And what's going to grab attention? The great thing about our show is the background is always different. You never see the same thing on the race. A lot of shows go back to the same set or the same type of environment - they're in a house or they're in a studio - and the backdrop doesn't change. The thing that's really exciting for me is that we're finally in HD. It's definitely going to add another layer to the show that I think will only draw more viewers because for a long time viewers have always said "'We love seeing the world through the lense of 'The Amazing Race'" and this time it's wider and it's more defined.

JH: The documentary of your ride across America in 2009 really shows what an amazing journey you had. How can people see "The Ride?"

PK: We've been working with Regal Cinemas around the country and they've been so incredibly generous. They gave us 10 theaters around the country and allowed us to provide 100% off the box office to MS. We sold out in LA and they automatically gave me a second theater and that sold out. We sold out in Denver and they gave me a bigger 450-seat theater. We sold out in every single location around the country. You can download it from the links that are on my website, www.NoOpportunityWasted.com or on ITunes and from Amazon. We're spreading the film out as much as we can. It was a labor of love and all self-funded and taken two years to complete and so far we've gotten some great feedback, which are also on the website. It was the hardest thing I've ever done, without a doubt.

"The Amazing Race: Unfinished Business" starts this Sunday at 8:00/7:00 on CBS.