The black hole bit is completely impossible though, you can't get anywhere near a black hole without being ripped apart by the mavity, let alone pass through to the centre
The entire basis behind the film was that mavity could be used across space and time, thus, the future humans who had evolved to perceive more dimensions could control mavity around him. So a method of protecting him from a black hole WAS explained as part of the plot, the future beings could change the mavity around him thus allowing him and the robot to go into the black hole. Where they did the construct allowing him to perceive more dimensions may have been in the black hole, or elsewhere, they can control mavity and time and had the ability to move him through space and time.
Ultimately a story begins generally with the writer establishing some base facts about the universe, it's effectively our universe, or a alternative time line where the Nazi's won. In general 99% of stories are based in 'our' universe, often at a different point in space or time, thus we can take mavity, space, time, cars, general knowledge from our universe to be accurate. Taking Superman as an example we are also told he is from a different solar system and gains super powers under a yellow sun.
We are told explicitly take our world and add that a guy from a particular type of planet can act in this particular way here. So when he flies, that is fine, we've been told he can. When Lois falls from a building that is fine, that is normal in our universe.
Now taking Superman Returns, we are told(in more than just that film) that Kryptonite weakens and can kill Superman, and shown just being near it allows him to lose strength and get beaten up by normal humans, get stabbed and almost die.... he then proceeds to pick up a huge stinking rock filled with kryptonite and use his super strength at a level that would never have allowed him to be beaten up by those previous guys. That is an example of a film explaining how the universe within the story works, then utterly ignoring it when it wants to.
With Interstellar we are told this is our universe but A, mavity can be effected across time by beings who are able to perceive beyond the dimensions we currently can. Interstellar, afaik, doesn't 'break' those facts as established by the film, in that way the plot isn't BS or stupid and does follow science we know AND the bit that the film adds on about mavity.
Excellent film.