What to do (if something) when someone gets your paper wrong What would be the best approach when a paper gets published referencing a work of yours, with a wrong explanation/assumption. 

E.g.


  "The tube lines by [the Mayor of London, 1863] are OK, but can only
  used on Tuesday, so in this work we traveled by cab".


This is clearly a wrong statement, probably formulated due to lack of information. What should one do in these cases, if you were the Mayor of London? 
My hunch says just ignore it, but I assume that for young researchers like me (unlike the Mayor of London) this can have a bigger impact, as if the first few references to our work are stating something wrong, people may actually stop using the tube.
If the paper is already published, the only thing you can do is to get the journal to publish a correction. This is usually a huge hassle and only justified in extreme cases such as if the paper under question is mainly a response to yours. Being known as a pain in the posterior is usually much worse than being cited in a misleading way.

You can also use your own future papers to set the record straight. "Contrary to BLAH 2018, BLAH 2016 did not advocate to eat all the cookies". In minor cases, I would not do this either.

Things are of course different if a paper is not yet published, in this case, you can just write a polite email to the authors. Of course, in many fields papers are not circulated early. You can of course also write authors of published papers and correct their misperceptions so that they will not describe your work wrongly in future papers. In any case, be polite and not accusatory.