CBS Philly reports 44-year-old Danny Ngo was arrested after the child was found alone in the Lexus Saturday night, screaming and sweating profusely.
The station says Bensalem, Pa. police were called to the parking lot at Parx Casino where they found the boy.
Bensalem public safety director Fred Harran says the child was checked out without any serious problems, but it could have been worse.
"It could have been a fatality," Harran tells KYW Newsradio. "This was 9:30 at night, it was 88 degrees outside. The temperature in the car was much higher than that, according to the officer."
Surveillance video shows the father, Ngo, was in the casino for about 40 minutes, CBS Philly reported.
"He thought he just ran in there for a few minutes," says Harran, "but it never is the few minutes that they think - it's always a lot longer."
Ngo is charged with reckless endangerment and endangering the welfare of a child. His bail was set at $100,000.