So this is a ripoff of.....

You mean the movie? No, looks too boring and predictable and requiring too much suspension of disbelief for a movie that also strives to be correct about the science behind it.

When you are a bad writer, just put in the script some zombies and aliens, dammit.

Bullshit. Energy isn't pulled from the ether it is limited and even if the recycler fairy gave them a carbon dioxide recycler it would still need energy which can't be created from nothing. Every pound you launch is costing upwards of 10,000. You don't build in enough excess to provide for and increase in required resources of 33%. The stowaway would need to be terminated quickly.

Yes they would have some extra supplies, but when it came to food it would have likely been 5 or 10 percent extra. But assume it was 50% extra. That would mean they had food for 3.5 people. If you then ration that to 4 people then you are starving to death 4 people over a 2 year period which was the supposed time they were going to spend going out and back. You just created a ship of 4 concentration camp victims.

What was really ridiculous from the very start was that the stowaway was not just someone that was knocked unconscious and collapsed in a place where he wasn't noticed, he was someone that supposedly collapsed and was then sealed into where he fell by someone on the outside that screwed a panel on top of him. Or that he survived the lift off while tangled in the mass of cables. If you assumed he really did accidently get hidden behind a panel, the lift off should have killed or at the very least left him with some serious injuries, probably some brain damage from a loss of blood flow to parts of his brain.