One proved costly and the other one could have led to a changing of the places on the podium.
Jeanette Gerrie (Christchurch) won the women's event by 67sec in 2hr 18min 36sec and defending champion Sara Macdonald (Dunedin) was second in 2hr 19min 43sec.
Erin Greene (Dunedin) was third in 2hr 23min 52sec.
Macdonald made the first error on the difficult Karetai track soon after the start of the 43km journey.
"I went off on a stupid line and spent the rest of the race chasing by myself," she said.
It gave the early initiative to Gerrie, who took advantage by sitting with the bunch in the men's race and being dragged along.
Gerrie (35), a Christchurch physiotherapist, stayed with the bunch as long as she could.
Conditions were wild on the peninsula, with the strong southerly making riding conditions difficult, and at times dangerous.
Gerrie thought she had the race in the bag before she made a mistake and was blown 3m down a bank 3km from the finish.
"I lost control and the wind blew me over," she said.
"I had no idea where I was. The wind was terrible and very hard to cope with."
By the time Gerrie had picked herself up, she could see Macdonald closing fast.
It was an error that reduced the gap but did not alter the result.
Men's winner Brendon Sharratt (Christchurch) is skilled on a road bike and was third in the New Zealand criterium championships last year.
But he enjoys mountain biking more and was keen to test himself against some of the best cross-country riders in the country, including Dunedin Olympian Kashi Leuchs.
Sharratt (27), a spray painter, set the pace from the start and quickly opened up a gap on the bunch of 10 who followed him.
Even a puncture after 15km did not slow him down.
"I could see the pack all the time and knew where they were," he said.
"When I'd fixed my puncture I was still a minute in front."
Sharratt won by the big margin of 2min 42sec in 1hr 56min 54sec from Ash Hough (Tauranga) 1hr 59min 36sec, Jon Richardson (Dunedin) 1hr 59min 38sec and Brad Tilby (Nelson) 1hr 59min 48sec.
The winning time was 7min faster than last year's and the first 12 riders all came in under last year's top time.
Hough, Richardson and Tilby split from the bunch through the tussocks near the Pyramids, rode together, and were only separated by the final sprint.
Leuchs finished 12th in the open men's grade in 2hr 07min 14sec.
One of the outstanding rides of the day came from 14-year-old Christchurch Boys High School pupil Anton Cooper, who came fifth in 2hr 00min 22sec and was first in the junior men's race for the South Island Cup.
Cooper is being backed by BikeNZ as a special talent and is being supported by sponsors in Christchurch.
The other top juniors also impressed, with the minor placings filled by Richard Anderson (Blenheim), second in 2hr 01min 44sec, Logan Horn (Christchurch) 2hr 03minb 37sec and Bradley Hudson (Christchurch) 2hr 04min 42sec.
Otago riders to win long-course events in their age groups were: Geoff Anderson (Dunedin) masters men, Kath Kelly (Roxburgh) open women, Bruce Jenkins (Dunedin) South Island Cup veteran men, Peter Green (Dunedin) veteran men (non South Island Cup).
