I would use it as a training opportunity....initially scale back on what you originally planned on doing, and use extra high-power rewards. Definitely keep the dog on lead.
If this was my dog, I'd start out working as far away from the distractions as possible, and make the reward so big that he really wants MORE. Start out working on something EASY and end on success. You can always go back later and do more, but don't keep working until something goes wrong!
Ignore the noisy little pains in the butt, don't even acknowledge their presence. Don't even make comments to your dog about them. Completely ignore them. When you pay too much attention to something, your dog gets the idea that it's something important, something to worry about, and he joins you in paying attention to the distraction.
--Regina and the GSDs:
UCDX von Sontausen Holy Grail (The BUNNY!) HGH, UD,RA,BN,GN, ASCA UD RAX High in Trial
PAM Monster Mike SchH2,UDX,OM1,TD,RE,VER
PAM FGDCh Ianna von Sontausen UDX,BH,TD,RE,PT (4.26.1998 - 2.11.2013)