As part of Luminato, 1,623 people gathered in Yonge-Dundas Square to play Neil Young's Helpless. This was a new Canadian record for largest guitar ensemble. The Guinness World Record is held by Germany at over 1,800 players performing Deep Purple's Smoke on the Water.

UPDATE: It looks like my data was not accurate. Apparently the World Record is held by Poland, where 6,346 people performed Hey Joe.