Elvis is driving a Dodge Charger but the gear shifter is for a Ford.
When Elvis first parks his red car near the trailer, the car is only up to the grass line and you can't even see it in the next scene when he opens the trailer door and enters. However upon leaving the trailer, you see the red car as he exits and it is now completely on the grass, right next to the trailer.
In all the scenes at the hangout, there is a band playing, yet none of the times are any of the guitars plugged in.
When Elvis slugs a guy and sends him sliding across the floor on his back and into an elevator, the guy hit the floor without enough momentum to slide as far he did.
During the first race, the pace car is shown in closeups with a driver and Miss Charlotte Speedway sitting on the top of the back seat during the warm up laps. In the aerial long range shots, the car is shown with 2 people in the front seat, along with a camera and cameraman in the backseat next to the beauty queen.