For good measure the Highlanders pivot banged over the sideline conversion although the rest of his kicking was patchy in the swirling conditions.
Slade was pushed out to the wing in the second half as Weepu came from the bench to run the cutter at first-five and even took the goal-kicking duties for the final quarter.
Slade limped off with 15 minutes left, which forced Victor Vito, who started the game on the openside of the scrum, to play on the wing.
Vito had previously scored a popular try in the 12th minute and did an admirable job in the No 7 jersey in the absence of Richie McCaw.
Guildford looked for work throughout the early stages of the game and you got the impression he was desperate to prove to coach Graham Henry he is worth another chance on the left flank.
When the young winger grabbed his second try in the 24th minute it locked up the bonus point for the All Blacks and ensured New Zealand were the only team in the tournament to grab maximum points from all of their pool games.
Canada's defence was woeful at times and the amount of first-up tackles they missed proved costly as it gave the All Blacks the chance to create space and run wild.
Bullocking blindside flanker Jerome Kaino was again in superb form and he carried the ball with plenty of vigour during the encounter and also bagged two tries to take his World Cup tally to four touchdowns.
The All Blacks' scrum was completely dominant and looked in ominous form.
Canada forced their way on to the scoreboard courtesy of a penalty from Ander Monro and a try from winger Conor Trainor just before half-time as the Canucks went to the sheds down 37-8.
Almost unbelievably Canada enjoyed a 76 per cent territory advantage during the opening 40 minutes but they struggled to turn it in to many points.
In the second spell Canada grabbed the first try, when Trainor went in again as rain began to fall and there may be some concern around Israel Dagg who limped off after only a few minutes into the second half.
The weather didn't help the spectacle either as the All Blacks made too many handling errors, while their passing was inaccurate at times.
Mils Muliaina lined up for his 99th test and he also inked his name on the score sheet.
The test was the first time two hookers had skippered opposing sides in a Rugby World Cup match since France played against Fiji in 1999 and it also marked the first occasion that Andrew Hore captained the All Blacks.
Halfback Jimmy Cowan became the 41st player to notch 50 tests for the All Blacks and grabbed a try of his own as he was solid although not spectacular and it still remains to be seen who the coaches' preferred No 9 is.
New Zealand 79 (Zac Guildford 4, Jerome Kaino 2, Victor Vito 2, Israel Dagg, Mils Muliaina, Jimmy Cowan, Sonny Bill Williams, Slade 4 cons, pen, Weepu 4 cons) Canada 15 (Conor Trainor 2 tries; Ander Monro pen, con)
Full match recap: