In Bridge, what is the punishment for misclaiming tricks?
The laws of Contract bridge try to achieve a result equitable to both sides (and not to punish), but in case of doubt, resolution might favour the non-offending side.

Laws 68-71 deal with claims (and there are alternative versions for the Club setting), and you can read about them here: http://web2.acbl.org/laws/rlaws/lawofcontractbridgecombined_2004.pdf (2008 version).

Quoting a paragraph from Law 69 (non Club, 2004 version):


  The objective of subsequent play is to achieve a result as equitable
  as possible to both sides, but any doubtful point must be resolved in
  favor of the defenders. Declarer may not make any play inconsistent
  with the statement he may have made at the time of his claim or
  concession. If he failed to make any appropriate statement at that
  time, his choice of plays is restricted thereby: 
  
  [snipped]


I believe there is also a provision which allows declarer to follow a routine/rational line of play which does not contradict the plays specifically disallowed, in case the claim is rejected. Of course, there are quite a few subjective words in the laws which might lead to different resolutions by different directors.

Perhaps in your case, it would probably be irrational for declarer to play the 10 instead of Q and dropping the J.

Disclaimer (pun intended): I am not qualified to be a director, so what is written here is just my interpretation. (Though I did get a chance to talk to some directors about this in the past few years of playing and what I write here is influenced by those discussions)