Will these Kentucky Derby bettors be appy?

Jockey Victor Espinoza celebrates atop of California Chrome after winning the 140th running of the Kentucky Derby at Churchill Downs in 2014.
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Jockey Victor Espinoza celebrates atop of California Chrome after winning the 140th running of the Kentucky Derby at Churchill Downs in 2014.

It's off to the races for iPhone gamblers.

Saturday's Kentucky Derby is going to be a first—because you'll be able to bet money on the race from an iPhone app. After Apple changed its policy in 2013, it took more than a year to figure out the legal loopholes, and for companies to develop apps. (Tweet This)

"It's a big development for the U.S. and the movement towards a more open, regulated real-money gaming," said Walter Hessert, co-founder and chief product officer of Derby Games.

Read MoreHow to bet on the Derby, and not embarrass yourself

His firm spent several months building the app, called Derby Jackpot, and then went through a "long process" with Apple reviewing the laws and licenses around horse racing. Then they had "a few back and forths to get the geolocation right," finally getting the app approved at the end of March, he said.

By incorporating social interaction and simple interfaces, Derby Games differentiates its app from the other more advanced wagering apps that have also launched this year. Other apps available for Kentucky Derby wagering are Xpressbet, TVG, and Twinspires—which is owned by Churchill Downs, the company that owns the host site of the Derby.

Google didn't change its rules, so Android users have to still use a Web browser. Hessert believes Apple changed its policy "as a reaction to the growing regulated online gambling business in the U.S."

In-app bets costs the same as at the track

As far as what cut Derby Games gets from each bet, Hessert wouldn't specify, only saying "we get a percentage of every dollar bet through our app or website, but for the user it's exactly the same odds and payouts as betting at Churchill Downs or any racetrack."

Read MoreCheck out the most expensive seats at the Derby

Moving the business from a mobile Web experience to an app-based one is going to be key to Derby Game's growth. "Mobile Web makes up just 14 percent of mobile activity—and it is dropping," Hessert said. "We believe that over the next 12-24 months, mobile apps will drive the majority of our business."

Xpressbet, TVG, and Twinspires

Rookie mistakes to avoid

As the chart above shows, the Derby brings much more extra money compared to a normal horse race weekend. This extra infusion of bets will basically be "dumb money"—people who don't know what they are doing. If you want to try to turn a profit, avoid some basic rookie mistakes. Derby Games co-founder Bill Hessert, Walter's brother, helped us with these tips to avoid gambling catastrophe:

Gray-colored horses: "People bet on gray horses because they visually stand out, but they aren't any faster."

Overhyped favorites: "The biggest favorite tends to have odds out of line with their chance of winning," because too many people on it.

The biggest long shot: "The odds for the biggest long shot should be even longer than you see," because lots of people take a chance on a big pay day.

Post position seven: "People just like to bet on lucky number seven, regardless of horse quality."