Weronika Vetrov threatens to blow up the station by igniting oxygen. Oxygen does not burn, it only supports combustion. You need a fuel.
You can't fist fight in space.
When there are only three crew members left aboard the ISS, one is preparing a sandwich on a counter top, the knife, the bread, the avocado spread and other items remained on the counter instead of floating through the station.
- Actually, it is shown in the movie that those items are attached to the counter top by velcro.
@1:09, the word "Canada" on the Canadarm is reversed, showing that the filmmakers flipped the image.
Around 41min, Gordon is outside the ISS and is at the end of his tether. The tether is hooked to one of the handlebars on the side of the outer wall. Gordon chooses to unhook himself rather that move the tether's anchor over to a second handlebar, closer to his position, which is clearly visible. There is no reason for him to unhook himself from the tether.