I was watching My Boss My Hero, and I could have sworn he said わかね instead of わからない-Is this feasible? Is there some dialect that drops off ない for ね?
It's fairly common for both
Your example has an additional contraction. When a vowel is dropped between
Then this undergoes the other contraction we already talked about:
Japanese is somewhat sensitive to length, so that
As for where this happens, I have to admit I'm no expert on dialects. But as I understand it, it's fairly widespread. I've read that it happens in and around Tōkyō, and I know it happens in other parts of the Kantō area as well. To be honest, I wouldn't be surprised if it happened all over Japan. (But the charts I found only mentioned the Kantō area.)
Changing ない to ね is routine in several dialects. So you'll hear things like 知らね instead of 知らない, or やらね instead of やらない.
Additionally, the character probably said わかんね, not わかね. ら and る will sometimes be rendered as ん when followed by な行 mora such as な, ね, or の. So you'll hear things like つまんね (instead of つまらない - つまんない is, of course, also used), どうすんの (どうするの), or なにしてんの (なにしてるの).