"I think from the players' point of view, we're looking beyond nothing else than competition for places," he said.
"You've got a chance this week, there's three big games coming up, you want to be in the team every week. You know you have to perform.
"Deccie made a great point at the meeting (today) that playing for Canada is a huge honour for these guys as well and they'll go out and give it everything.
"It's a Test match and it's up a level from anything we've played since the tour last summer and we'll have to perform well.
"We've gone through some of Canada's matches - they've played Argentina, America and Scotland recently.
"With the help of Merv (Mervyn Murphy) and the coaches, we'll know them inside out...in terms of ball carriers, what carries they do, little stuff that goes into it. Tuesday to Thursday is when all the homework gets done."
The big news selection wise for this weekend's tie, of course, has been Keith Earls' nod for the full-back berth.
O'Callaghan said: "I'm absolutely thrilled for him. It's great. He's worked really hard, done all the extras. He's a bit of a light for younger fellas coming through in academies.
"I'm thrilled for him, it'll be a great day for himself and a great day for his family. The fact that it's in Thomond makes it extra special."
So what are the the differences between Declan Kidney the Munster coach and Declan Kidney the Ireland coach?
"There's certain things you might be used to, but when it comes to motivating a team and a dressing room, Deccie's well able to do it. He always looks for high standards and he's set that here again.
"We've week two down and we couldn't have asked for any more from the management and staff and we're in a good place now.
"Hopefully on Saturday we'll put in the performance that the work in the last two weeks merits."
And what of the Thomond Park factor? O'Callaghan is clearly relishing the chance to don an Ireland shirt at his provincial ground.
"I know, as a Munster man, we went out (at Thomond Park) against Montauban and didn't play too well.
"You'd be glad to get back there and put in a big performance for the crowd. They're passionate down there and will get right behind the team," he enthused.