Canadianisms.
Speaking of things that Canadians say and don't say, naturally when other folks here in the States hear that I lived in Canada, they immediately start tacking "eh" onto all of their sentences just to tease. (Ever seen that Molson commercial where the guy shirts his co-worker for saying "eh" too many times--I love that one.)
But in Western Canada or at least in Alberta, the only people that tack "eh" onto their sentences with any regularity are the older generation. Similar to the use of the metric system, the word "eh" isn't necessarily endemic to all Canadian conversations. If one were to write a story with younger Canadian readers and throw that in for veracity, it would come off as forced.
(BTW, for an example of fictional Canadians who don't come off with the forced "eh" dialogue--the For Better or For Worse family, drawn and written by Lynn Johnson. They are Canadian, but they don't run through their comic strip sprinkling metric stats left and right, nor do they use the word, "eh" overmuch. Instead, you can tell that they are Canadian by their actions and environment and cultural touchstones--such as Grandpa Jim's participating in Remembrance Day Parades. The dialogue isn't a "stereotypical Canadian" sort of dialogue, but natural everyday dialogue. Sometimes it gets a little silly, or sappy, or wise or whatever, but it's always something I could imagine real people saying.)
I think this is where the advice that you should do your research but not make your readers suffer for it comes into play. Whatever facts that one finds should be sprinkled in like a potent spice.