Revealing mistake: When the apes jump out of the lab windows out to the street, they don't cast a shadow on any of the glass except the ones on the ground floor.
Revealing mistake: When Will's dad's Alzheimer boosts and he smashes the car driving in reverse, the headlight of the car behind is blatantly loose to increase the drama of the crash.
Answer: It's not necessarily a sign that the orangutan understands human motivations. It could be, and probably more likely *is*, a sign that the ape has shown its intelligence previously during its stay in the habitat, was abused by the humans as a direct or indirect result, and was subsequently conditioned to play dumb.
Phixius ★