In the opening scene, the man grabs the handles of the double doors leading to the room where a fire rages. He opens the doors and gets blasted by the backdraft. In real life, he would have burned his hands on the handles and thus would never have opened the doors.
Ron Cramer is described as having had two felony convictions (burglary and grand theft auto). Later, when caught with a concealed handgun, he says that he has a permit for it. Florida does not issue concealed handgun licenses to anyone with a felony conviction, and anyone holding such a license automatically has it revoked if convicted of a felony after having received the license. Additionally, gun ownership by anyone with a felony conviction is prohibited under federal law. The police make no mention of any of this and don't charge him with any crime.
When the water heater launches, the base is shown intact. For the water heater to launch upwards, the bottom would have to blow out. This would result in a cloud of live steam venting directly into the camera.
When Delco is dusting the piece of glass for fingerprints and looking at a computer monitor, we see part of the manufacturer's name on the back of the monitor. A moment later, we see the back of the monitor from another angle, and the manufacturer's name is digitally blurred out (presumably due to concerns about product placement).