As noted by @Stu:

On the regular site, going to https://en.wikipedia.org/wiki/Cantilever_brake redirects to https://en.wikipedia.org/wiki/Bicycle_brake#Rim_brakes. Makes sense.

But on the mobile site there's a weird outcome. https://en.m.wikipedia.org/wiki/Cantilever_brake redirects to https://en.m.wikipedia.org/wiki/Cantilever_brake#Rim_brakes. Note that instead of Bicycle_brake#Rim_brakes it's redirecting to Cantilever_brake#Rim_brakes which is nonsensical since it's the title from the redirect and the section heading from the actual article. I noticed because Google webmaster tools was kicking off a bunch of errors.