Around 27 minutes, the Brujo goes to the unconscious boy and leaves a doll on his chest. Moments later when the raven flies over, the doll is gone. When the mother walks to the boy the doll is back.
On the rafter, viewed from above, the bird is a different bird, from the bird viewed from below.
at 27.42 there are strings visible on the stuffed bird as it flies around.
At 28:20, the bird handler's shadow can clearly be seen in far left of screen. He is holding a treat and you can see the bird flying to his arm before a cut to where bird is flying into building.
When the hawk lands on the boys arm you can see a leather sleeve underneath his shirt sleeve to protect his arm from the claws.