This is currently the case on beta labs
Visit http://en.m.wikipedia.beta.wmflabs.org/w/index.php?title=Nunilo_and_Alodia&debug=true in beta, click on an image and watch it explode with a JS error.
Seems to be encoding related as works fine on
http://en.m.wikipedia.beta.wmflabs.org/wiki/San_Francisco
Version: unspecified
Severity: normal