Despite the Australian World Champion duo starting as favourites to win after heading the women's and men's fields in qualifying two days ago, China's Xuetong Cai snatched victory away from Crawford while Johnstone was edged off the top podium step by his main World Cup rival this season Ryo Aono of Japan.
NSWIS Halfpipe Head Coach Ben Alexander was unable to pinpoint the difference between Crawford and Cai and Johnstone and Aono except to say that a few things did not go the Australians' way today.
"I suppose Holly and Nathan did not execute today quite as well as they can," Alexander said.
"They both rode very strongly, there wasn't anything major in particular but sometimes it happens."
Both Australians tried to apply more pressure after their first runs by upping the level of difficulty with their tricks.
Johnstone, who was leading Aono after his first run, which Alexander described as "impeccable", tried to step up a frontside 720 to a frontside 1080, a trick he used with huge success to win last month's World Championship.
But the AIS/NSWIS scholarship holder was unable to cleanly execute the trick today.
Aono responded with a run that Johnstone later labelled as "unreal", recording a highly impressive 28.3 points while the Australian could not improve on his first run of 27.7.
Johnstone's second means that the gap between himself and Aono in the World Cup standing has widened from 540 points going into Calgary to 740.
However, with 2000 points still on offer and two rounds of competition before the close of the season, the Australian knows that the chase for the World Cup Champion "Crystal Globe" is far from over.
Crawford suffered a similar result, changing up a fourth trick cab 360 in the first run to a cab 720 in the second trip down the pipe.
Like her teammate, she was unable to execute her run cleanly and lost momentum for the rest of the run.
Crawford's consecutive silver medals over the past two events now elevates her from eighth place on the World Cup standings to the number two ranked rider, only 160 points ahead of China's Zhifeng Sun in third.
Also in the mens final, 17-year-old Vancouver 2010 Olympian Scott James recorded a PB World Cup result, finishing the event in a very credible eighth place.
The AIS halfpipe team now travels to Bardonecchia, Italy, for the season's penultimate event on March 11.