Well, that's because we're sane about how we register voters
That is, Elections Canada (a non-partisan arms-length department of the government) makes up the voter rolls. You don't need to register to vote... instead, you're registered to vote by the state. Obviously, there are ways to game the system, but since it's pretty much a given that you have to have paid taxes in order to show up on the rolls (or at least have shown why you DIDN'T have to pay taxes), as well as being a citizen, it's really hard to register people who don't exist.
Mind you, the system used to be better than it is now; the creeping moronism of "efficiency is a universal good" has meant that the old system, where Elections Canada would send people around to knock on every door in Canada in the lead up to an election (or at least on every door in the place where a vote was taking place) made for an even more accurate list of voters.
Dead people, pets, and foreigners generally only get to vote in party elections, not in actual elections... and foreigners are free to vote in party elections, as long as the party's constitution permits that; they are private associations after all and their rules are up to them, not up to the state.
You might be thinking 'how insanely labour intensive that is', but that's democracy. Democracy is by its nature labour intensive, and when it gets to the point that it's not labour intensive, you have to wonder if it's still democracy.
