Sure, that's always a possibility, I won't lie to you and say it doesn't happen.

Although it is extremely rare at autocrosses, especially NASA-MA ones (we have a far better safety record than some other autocross groups around here, but that's another discussion entirely.)

Here's an idea... you're the driver, right? Drive the car within YOUR limits, no matter how low or high they may be, and no matter how fast or slow you go as a result. Don't take any risks and don't do anything you aren't comfortable with. THAT's the way to not hit anything.

Plus at Summit Point there would be an instructor in the car with you the whole time hopefully keeping you out of trouble. See "Group 1" here: http://www.nasaracing.net/hpde.htm

Otherwise it'll just use up some tires/brakes/gas. Big deal, that stuff is meant to be replaced.