These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: 10,000 BC
Critical Research Failure: Averted in that the filmmakers already knew they weren't making a historically accurate movie. The idea of the movie being set in "10,000 B.C." was merely a promotional/selling point for dramatic purposes.
Nightmare Fuel: The Attack of the Terror Birds. Just think what it must be like to stand in that tall grass, unable to see anything around you, and then suddenly realize you're being stalked by stealthy predators, you can't see where they're coming from, and any attempt to move could lead you closer to your death.
So Bad, It's Good: Many people only see this movie to laugh at its many, many, many errors. Though others see it as deliberately invoking Rule of Cool over any historical accuracy.