Considering that the PR's about the fighters being in the movie were not only put out on the news wire but posted on most of the top MMA sites such as MMAweekly and Sherdog, I am sure that if the management or the fighters did not agree to the PR going out or to the fighters being in the movie, that Imperia would have been in serious trouble very fast after the announcements went out.
If you are a law fan, you should know that agreements don't necessarily have to be written or signed. There is such a thing as "verbal agreement". Whatever the agreement was, I am sure that the fighters and managers agreed to terms and to the PR or management of those fighters would deny their involvement and probably follow up with a lawsuit against Imperia.
Now you can go back to Law school...
"Contract 1) n. an agreement with specific terms between two or more persons or entities in which there is a promise to do something in return for a valuable benefit known as consideration. Since the law of contracts is at the heart of most business dealings, it is one of the three or four most significant areas of legal concern and can involve variations on circumstances and complexities. The existence of a contract requires finding the following factual elements: a) an offer; b) an acceptance of that offer which results in a meeting of the minds; c) a promise to perform; d) a valuable consideration (which can be a promise or payment in some form); e) a time or event when performance must be made (meet commitments); f) terms and conditions for performance, including fulfilling promises; g) performance. A unilateral contract is one in which there is a promise to pay or give other consideration in return for actual performance. (I will pay you $500 to fix my car by Thursday; the performance is fixing the car by that date). A bilateral contract is one in which a promise is exchanged for a promise. (I promise to fix your car by Thursday and you promise to pay $500 on Thursday). Contracts can be either written or ORAL."
