If you are currently on the market it might help! The traffic from the 3 day festival may generate a buyer that would have never known about your property. If they like the area a qualified buyer may just decide that they would like to live in the area. The additional exposure may not be a bad thing. You may want to ask your neighbor to have flyers on home or have flyers at the street available for people that show interest in your home. You never know where your buyer is going to come from.
Will having flyers availble get your home sold? I don't know but not having them will definately not bring a buyer.

After the 3-day festival is over, none that I can see. Is your property on the market now? Will it be on the market while the festival is going on? If so, I might suggest you wait until the festivities are over, if you can. If this is the first and last time your neighbor holds the festival, it's a non-starter in the realm of property value.