Alien Worlds? Whatevs
The Movie: Characters frequently step onto alien worlds with zero protective gear. For example, Bones McCoy and Carol Marcus step off onto a "planetoid" to open a torpedo and are just walking around like it's their home planet.
Real Life: There are thousands of worlds in our solar system, including planets, moons, asteroids, and comets. Every last one of them would be a death trap to a human strolling around with no protective gear. Heck, there are places on our own planet that would make short work of us — the bottom of the ocean, the Poles, inside volcanos (despite what Spock would have you believe). Our neighboring worlds are tortured by extreme temperatures, relentless radiation, toxic gases, hellish atmospheres... and that's all without getting into gravity. How is it that all the Star Trek worlds possess the same gravitational force?! Are we really to believe that they are just randomly the same mass? The most egregious g-force sin is the case of the "planetoid," which would be, at best, the size of Pluto (compared with Earth in this image). Each step Bones and Carol took should have launched them to the sky, but instead they walk around like they had evolved for billions of years on that lil hunk of dirt. Puh-lease.