My slice E turned to contain not one, but two missing streets, it also had some idiosyncratic street numbering on Prospect Street and Weredale Park (whose name I'm not clear whether it includes "Street" or not).
There was also an odd footpath extend from the corner of Prospect. It took me a while to figure out that it did not extend to Weredale Park (at first I thought it was the same as this footpath), but it in fact, does not even connect directly to the alleyway behind Clandeboye Avenue, but to the Weredale House parking lot. Also found a few permissive access shortcuts.
What this really outlined for me is that Westmount street names will be thoroughly frustrating to edit because they must be entered billingually and it is not entirely obvious whether the basic name should be French or English. Also, the street name indications on the ground do not include the "street"/"avenue"/etc. specific. AFAICT, most of the North-South (or rather NW-SE) streets are "Avenue" and the E-W (SW-NE) are "Streets, with various other oddly placed ways having other names (e.g. "Road", "circle", "crescent", there is even one called just "The Boulevard"). I've changed a few, but I'm not clear whether I should change the matching addresses too. This is really frustrating (though the street name on the envelope does not matter in the end: any addressing method is valid anyway, and you can generally leave out the part that changes anyway!).