After tumbling out of the SUV, the two boys were flown to a local hospital.
"They had some bumps and bruises yesterday, but nothing life-threatening," Utah Highway Patrol Corp. Todd Johnson said.
The five-year-old was in a booster seat, but the three-year-old was not, but was buckled into a regular safety belt, according to a Utah Highway Patrol (UHP) release.
While the mother was driving, the car's tailgate opened and items started falling out of the SUV onto the highway. Two of her four children got out of their seat belts and presumably were trying to keep the items from falling out, according to UHP.
But while they were trying to prevent items from falling out of the SUV, they fell over the seat and out of the SUV, onto the freeway.
The two boys only sustained minor cuts and bruises.