I can totally appreciate the desire to pre-ride a course for a 'cross race and wanting to do it while a race is happening if you arrive late to the venue. It can make all the difference. However, NEVER interfere with the ongoing race! (Does that even need to be said?)
Last Saturday in Tulsa, on the final turns of the final lap of the women's race, fellow racer Miranda and I encountered a group of guys (6-8?) on the course, warming up for the A race. The two of us had been racing each other for the last 50 minutes and we were less than a 1/4 mile from the finish.
I yell, "Racers coming through!"
Dude says, "Where do you want us to go?"
Seriously? Get out the way, duh!
As we passed through them, they were working on getting off the course. To my delight, one of them hit a culvert and went over the bars. If I hadn't been buried (and focused on a strong finish), I would have laughed and said, "It serves you right!" I hope he didn't get hurt, but I am still snickering.