Cassidy posted slow-motion footage of the crash to his Facebook page, along with photos of a cut and bruising on his left leg and of a huge dent he left in a Volkswagen car.
He also wrote: “As you all know I had a little off at nw 200. I’m all OK just bloody sore.
“I was behind a rider and had just clicked 4th I believe his bike cut out or something on the 1st right after the start ... The marshals said the same thing too. He pulled to the left then looking over his left shoulder not knowing I was going round him and we collided together.
“Unfortunately nothing I could do at that sort of speed. Big thank you to everyone for all support … all the medical staff did a cracking job.
“Went up around 25ft and landed in the garden on someone’s car.”
A statement from race organisers said: “The information from the NW200 medical team indicates none of the competitors sustained serious injuries, but two have been taken to Causeway Hospital for assessment and treatment.”
Thursday’s racing had Glenn Irwin set a lap record to edge out Davey Todd and secure a ninth consecutive NW200 Superbike win, equalling the all-time tally of victories in the premier class.