The event raised about $5000 for the preschool, which will be used to buy and install outdoor climbing frames by Christmas.
Lake Hayes resident Roger Grant, driving "The Flying Coffin", and Team Road Runner won the overall derby prize, the first Lakes District win in three years.
The ground-hugging cart took 200 hours to develop and was purpose-built.
It was driven lying down and head first, just centimetres from the road and reached speeds of up to 70kmh.
Mr Grant said the cart clipped a spectator's foot as he hit the kerb past the finish line, on Ramshaw Lane.
St John Wakatipu officers treated a 50-year-old Italian woman.
Her foot was X-rayed at Lakes District Hospital and she was discharged on crutches.
Mr Grant sustained whiplash as he tried to avoid the woman.
He was discharged from hospital after a precautionary X-ray and assessment which would be reviewed in a few days, Mr Grant said.
"I got a little bit of compression on my spine, but I've been checked out and we'll be back in the race next year with two entrants.
"Any accident that happens is a learning curve and we just pick up our game next time.
"It's a good community event and needs to be kept going."
The event was organised by preschool office manager Gerdi Schumann, president Carole Watts and parent Tim Young.
Ms Schumann said everyone had enjoyed themselves and some parents were inspired to enter the derby next year.
Up to 14 competitors, including three from Dunedin, raced from the starting line outside the preschool on Durham St, straight on to Surrey St, then took the right turn to Villiers St and on to Buckingham St, past the crowds of spectators and to the finish line.
Bargain hunters flocked to the local designer sale in the Athenaeum Hall, where Decode, Tamsin Cooper, Jane Sutherland, Three Bags Full and other brands set up shop.
Home baking, plants, face painting, sausages, kebab and refreshment stalls enjoyed brisk trade while eight scarecrows, made by preschool children were sold, some fetching $40 and $50 each.
