After failing to set up Swaggervel in Laravel 4.1, I upgraded to 4.2 using this upgrade guide which got it (mostly) working. Swagger UI worked to before modifying existing code annotations but occasionally, the links it generated seemed to break. The error message sounded like jQuery wasn't loaded at first because it didn't recognise the '$' token. However, if you opened up a raw JSON file in Chrome, some of the JSON was being stripped which made the JSON invalid.
To fix, you can just delete the JSON files instead of relying on swagger to rebuild the JSON properly (