When they are driving the horse onto the show grounds, the first scene shows a horse in the trailer with a shorter mane, typical of the type seen in eventing. They cut away to the cab of the truck, and when they return to the horse, it's clearly a different horse with a much longer mane. They cut away again, and when they return, the mane is short again.
Sitting at the bar Mr. Foster orders a bottle of Jose Cuervo Matt says "I thought you quit drinking whiskey", Jose Cuervo is tequila.
When Charlie is being raped, she pulls out of character by obviously scratching what must be an itchy nose.