A plus marketing and Nether Flame Sauce
One of my rules for good advertising is how many senses can you hit?
Having special limited-time specific food relating to the movie, like Nether Flame sauce or Apple Cake McFlurry, which hits.
Then you create a lasting moment of the meal. That would be the toy, unless you tried to eat it.
Finally, they add it as limited-time meal, not as a kids’ meal. This just helps to reduce friction when ordering, especially for people who don't have kids.