Continuity mistake: In the scene where Heather runs through the fairground she grabs onto the back of the Ferris wheel seat and is taken up in the air. Leatherface throws the chainsaw at the cop and the next shot shows Heather coming back down the other side of the Ferris wheel. But she should be on the inside of the carriages as it just spins round on an axis. These kinds of wheels don't "twist" at the top otherwise the rider would just be staring at the inside of the wheel the whole time.
Plot hole: The beginning of the film takes place in 1974 right after the original Texas Chainsaw film ends. Right after the house is burned, one of the townspeople takes a baby who survived the fire who is Heather. The film then takes place in 2012 but Heather seems 20 years old and should be 39.