Here is a list of issues with unclear route ends, and some intermediate waypoints. End signs exist for some routes covered by GMSV, so I haven't included those routes on this list.
SK 2 -- Intersects SK 936 near its north end, around the location shown in the HB. Google Maps shows the intersection location, and GMSV shows that intersection is with SK 936. Only Mapnik doesn't show the intersection at all. The only thing missing is open-source coordinates for the intersection.
SK 21 -- This is just a note that Mapnik appears to be following a long-bypassed old alignment, between newly-added waypoints RR233 and TR462 via Carruthers. Every other map I've consulted, including the latest official road map and the online Highway Hotline map, shows SK 21 following the route in the HB. I'm satisfied that Mapnik is simply wrong on this, no need for further followup, but it does underscore our not taking Mapnik as gospel truth.
SK 35 -- North end very unclear, with Mapnik showing it going well northeast of the endpoint shown on the provincial paper and online Highway Hotline maps. HB now truncates the route to a guesstimate of the north endpoint based on the official maps.
SK 102 -- North end within Southend unclear.
SK 106 and SK 120 -- Both routes intersect Harding Road, which may be or once have been SK 928. GMSV indicates the junction on SK 106 is unsigned; no GMSV coverage of that part of SK 120. No biggie if we have to settle for HarRd waypoints on both routes.
SK 123 -- North end really unclear. Online maps differ on where and how far the route goes north of the Saskatchewan River, including whether it passes through Pemmican Portage village or instead bypasses it to the west, and its endpoint in Cumberland House. An added complication is that the provincial Highway Hotline shows 123 following a winter road (not shown in other mapping) southeast from the Cumberland House region to SK 9 near the Manitoba border.
SK 165 -- SK 935 supposedly intersects with 165 in the Hall Lake area, but I'm unsure whether the intersection is located where the HB has it, or another intersection in the vicinity. No GMSV coverage.
SK 211 -- East end unclear.
SK 212 -- West end unclear (at road's end, or at park boundary).
SK 220 -- HB has west end east of park fee booths, but could route end at or west of booths?
SK 221 -- West end probably at park fee booths, where HB has it.
SK 240, SK 263, SK 264 -- Do routes end at Prince Albert NP boundary, or at fee booths, or continue into the park? 2009 GMSV imagery indicates 240 ends, along with its pavement, at the park boundary. I didn't see similar End signs on 263 and 264 whose pavement continues into the park, though neither did I recall seeing route markers inside the park. If the routes do not end at or near the park boundary, does SK 264 end at intersection with SK 263, or continue northwest as OSM indicates?
SK 255 -- North end in Tobin Lake unclear.
SK 261 -- GMSV confirms the route exists, and extends both west and east of SK 4, but not how far in each direction.
SK 305 -- Waypoint for what appears to be Old SK305/784_E could use a check on whether it remains an intersection with SK 784; the recent bypass of that former 305 segment is still a bit of a moving target, with a new interchange with SK 11 in progress, as well as a realignment of that part of SK 11.
SK 310 -- Is the intersection marked SK740 indeed with highway 740? (Mapnik is an outlier on that road being a numbered highway, and the provincial highway map is silent.) Ditto SK745 farther north. More perplexing, Google Maps and the provincial highway map have SK 743 intersecting at waypoint SK743?, while Mapnik and 2009 GMSV have it at waypoint EdmRd -- maybe SK 743 was moved?
SK 324 -- East end in Mayfair probably at Railway Ave. where Mapnik places endpoint, but no GMSV coverage to confirm.
SK 340 -- One intermediate waypoint is marked SK685?/781?, but number of intersecting route is unclear. 2013 GMSV imagery shows it as SK 685.
SK 354 -- North end unclear, whether it ends at SK 732/733 junction, or continues a little west along SK 733 to Railway Ave. in Dilke.
SK 378 -- Disagreement among maps about intersection with SK 686, east of Rabbit Lake. Official road map and Google Maps have it at waypoint SK686. Mapnik, 2009 GMSV, and 2008 MapArt paper atlas have it at hidden point +X123456, east of Meeting Lake (waypoint MeeLake). As with SK 21, I'm comfortable disagreeing with Mapnik, in favor of official and other maps showing a more recent routing for SK 686, no need for further followup.