If Kate was sent into the Cube to find Alex Trusk, you'd think she'd know a little more about them than their name, like maybe that instead of being a Russian male, that they're a blind Korean(?) female who goes by the name "Sasha" via an obscure Russian nickname route.
If Max and Julia are in an accelerated-time area, wouldn't they have just had their sex Really Really Fast, rather than dying of old age while having it?
That's not how relativity works anyhow, but due to movie physics they're perceiving time as normal when, in actuality, it's moving very fast relative to them. It doesn't make any sense no matter how you slice it, unless they emerge normally at the end.
How about the whole all the cubes converging at the time shown on the watches. How does that make any sense in a world where time is completely relative and not entirely linear?
Notice how some cubes exist in relative-time. meaning that things move faster inside them relative to an outside observer. Jerry exists in several versions due to quantum probability (two possibilities exist instead of one) but each Jerry has a watch that moves according to the time-cubes time-zone. if Jerry1 goes to a "Fast Cube", walks around in it, draw something on it, yawn and comes back... his watch would show that he spent a full hour inside it, even though it felt like a couple of minute. but when Jerry2 would go in a "Slow Cube" for 5 seconds and come back, it would look as if he was also a full hour inside as well. that way, it is possible that two watches reach the same cube and both show the same time if they went on cubes that re-synchronize their time. so if the cubes have a "Time-Conservation-Mechanism" then every choice Jerry1 would make would bring him in the end to the same time as Jerry2
We are shown that time is very malleable inside the Hypercube, to the point of allowing alternate temporal versions of the same person to exist at once. But how is it then possible to determine a precise point in time when the Hypercube collapses?
The time until collapse could be based on the objective, external time that those observing the cube are existing in. Thus, lifetimes would pass in (subjective) decades and (objective) seconds, which is why the observers weren't too surprised at the end: given the almost infinite branches of time that are possible in the Hypercube, at least one person would fulfill the mission properly.