The scrumhalf scored his first try in the ninth minute with a superb run from deep inside his own half before going over again in the 17th and 20th minutes.
The Springboks ran in six tries in the first 27 minutes before things went from bad to worse for Canada as substitute lock Josh Larsen was shown the sixth red card of the World Cup for an illegal shoulder charge on the neck of a South African.
Playing against 14 men for more than 40 minutes, South Africa touched down four more times in an overwhelming victory.
There were also tries for Damian de Allende, S’Busiso Nkosi, Warrick Gelant, Frans Steyn, Schalk Brits, Damian Willemse and Frans Malherbe, while Elton Jantjies landed eight conversions.
Flanker Matt Heaton’s try just after half time did ensure Canada got on the board, with just its second try of the tournament.
Since losing its opening game of the World Cup to New Zealand, South Africa has beaten Namibia and Italy, meaning it needed a bonus-point victory — for scoring four or more tries — to secure its place in the knockout stages.
And with 13 changes from the side that beat Italy 49-3 Saturday, the Springboks had no issues regularly carving through the porous Canadian, which had lost its first two games by an aggregate of 111-7.
“There’s a lot of guys who haven’t played for a while so it was scrappy at stages, but I can’t moan about 10 tries,” said South Africa coach Rassie Erasmus.
“Obviously, they got a red card which made it a little bit easier for us. Overall, not too bad, especially in this humidity.
“Sometimes you get to over exaggerate with the play, but I thought we kept it really simple tonight which was a good thing.”
Growing into the game
After conceding 48 points against Italy and 63 against New Zealand, Canada would have been hoping to put in a better defensive display against South Africa.
But all hopes of a more resolute performance went out the window as De Allende scored after just two minutes thanks to strong running from man-of-the-match RG Snyman, with Nkosi doubling its lead just three minutes later.
With Canada reeling, Reinach dissected its defense to eclipse the fastest World Cup hattrick, record previously held by Chris Latham, who crossed for a third try in the 25th minute against Namibia in 2003.
To its credit, Canada showed character and grit to restrict the Springboks in the second half and make its own mark on the scoreboard.
“It was very tough,” said Canada captain Tyler Ardron. “We couldn’t get our hands on the ball for those first 30 minutes or so.
“When they had it they did some damage. I feel we grew into the game and probably the last 50 we really put a better performance out. It’s never helpful to get a red card but we just pulled together.”
For 38-year-old South Africa hooker Brits, the World Cup so far has represented a triumphant return.
Brits originally retired in 2018 and had a place at Cambridge University lined up, but he was convinced to return to rugby by Erasmus.
He played at number eight for the first time in more than a decade when South Africa beat Namibia 57-3.
And after scoring against Canada before limping off with an apparent calf injury, South Africa captain Siya Kolisi hailed Brits’ influence on the South Africa squad.
“(Brits) has really been amazing,” Kolisi said. “Especially for us younger guys, he lifts us up.
“He’s got a lot of experience which is very important. It’s something we really needed as a team. And he’s always encouraging so he puts the team first before anything else. And as you can see, whenever he gets the opportunity, he really enjoys himself.”