Rob is right, Sound is extreamly important. if you must record on location where you have a lot of background noise then plan ahead.
one option is to go on location a week before and shoot the location with video and audio, then bring your actors to a chromo key studio and shoot the scene. You can add the background sound you want by using foley sound. this will cost a little more but will produce a much better film.
2nd option, fire your sound guy.
3nd option spend thounsands on post production.
