It's routine in the "outside world" for IP you created while working for a company, belongs to the company. Any credit or extra financial reward is up to your contract or the "decency" of the company. Entertainment companies are NOT famed for their generosity!

That said, a mere $5,000 when YOUR creation has a film based around it, is pretty damn cheap! And not inviting creators to fancy events just seems unnecessarily cruel and vindictive!