Good question. My daughter and I have done all the EEC's and I'm not sure I can answer this one.
Last year was the first year they had the obstacles integrated into the 5k portion. So do they give you 16mpm to run and complete the obstacles too? And then the scavenger hunt takes you back through the park.
They usually have a lot of waves for the starts. Individuals go first followed by many waves of teams. Wave start positions seem to be based on bib numbers and bib numbers seem to be assigned by order of registration. If you registered early, then you will be starting sooner and the 16mpm issue shouldn't come into play because there will be a lot of people starting way behind you.
If you you were the last team to register and start at the end of the last wave, then the 16mpm could come into play. But, it seems that Disney has gotten a lot more liberal with pace and if you are making steady progress, will probably allow you to continue.
Good luck!