Translation is an inexact science. The translatability of humour per se depends quite a lot on how you actually define translation - puns are, of course, unlikely to have word-for-word parallels, and jokes which rely on cultural references may not work even in different areas which notionally speak the same language, but if the texts are reasonably unrelated to the scene in hand, it may well be possible to work in a laugh at the same point for a completely different reason; this is a legitimate piece of functional translation. In media such as film and TV, where there are additional constraints of time and timing (for dubbing) and space (for subtitles), quite a high degree of information loss is almost inevitable. In practical terms the film translation business is almost entirely accountant-engineered - especially in cheesy b-movies - and rates are low enough that decent translators get out of it into something with less cachet but higher rates and less stringent deadlines when they can, so quality is not all it might be.