First of all, a very great plugin. I was planning to write one myself, but I found this nice work of yours. Good job.
Embedding works fine so far, but there is an issue with the widget. It displays a correct list of tournaments for my subdomain, but when I press 'Join', it comes up with 'ERROR: Invalid tournament'.
I have tracked down the issue to wrong url being called via curl (for which API does not return results).
What should be generated: