The checkpoint had to be prematurely closed and traffic diverted through Ponatahi Rd after a 31-year-old Belmont woman was hit by a bus on Kitchener St and the road closure was causing delays.
The majority of the 10,000-strong crowd were well behaved, said Ms Watson, although there were eight arrests.
"More people were arrested because more police were there and we decided to stamp out early, and the tolerance level was lower. We did send a bit of a message."
Most festivalgoers had gone home by about 9.30pm.
Toast Martinborough's decision to swap leftover festival francs for vouchers rather than bottles of wine meant fewer people were drinking in the Square after wineries stopped selling alcohol at 6pm.