About the time travel the way I see it:
Mass IS. Although not a exact contant figure, it's not possible to travel trough time and run into yourself. You can only be at one place at a time, as you can only excist once at a time. If you would be made of some atoms (or polygons?) you'd be a part of creation. Whether it would be a a god that created everything, a big bang or a computercompany like Nintendo. The input never changes, nor do the consequeses of the that creation event, as they are related to each other.
The data is there and shall remain the same amount at all times. There may be events that drive the data or input in a different way, but the total always sums up to 100%.
Going back in time and have a duplicate of yourself would interfere with the whole world, universe or even some multiverse (parrallel worlds?) if excisting. Having to Link's would make another character to dissapear, or something similar.
Therefore, you can't go back in time, only forward (which is nothing new, we do it all the time, even now).
But, according to the story you ended up at the same time and place (about the same time and place at least, at the very end of the game) when you put the sword back in the pedestal, meaning you didn't travel back in time as this is not possible, but you travelled forward through time, which loops on itself at one place or time or event or another.
It has to, as we witnessed Link to (re)appear at the Temple of Time or the Courtyard of Hyrule Castle.
The loop is in the flow of time itself, not in some magical part of the story like the Ocarina of Time or the Master Sword.
The Ocarina lets you inluence how much time would be travelled, as seen in Majora's Mask. The Master Sword keeps you alive through this millions of light-years during journey. Or something. Maybe you can use the MasterSword to cut holes in space to create wormholes? -----> read on below....
The most basic form of time travel is to bend the flat parts of space itself, fold them together and make a gap in both flat spaces and go through. Unfold the space again, close the gaps and appear where you would have wanted to go in the first place. This way you can travel faster than a straight line from point 'A' to point 'B', by creating a shorter (straight) line. Then, if you could somehow pinpoint your current position in time and space, as well as the place you'd like to go and where that place would be in space-time, you could go there pretty fast. Not in zero time, but infinity close to that.
Being in the Temple of light for seven years passed in an eyeblink for Link.
This makes it possible to beat Ganon (seal him away, not killing him) and still be a kid, as well as having the Ocarina when you were walking around in Termina.
Timetravel is a difficult subject, but I don't think Nintendo made any big mistakes or errors with this.
Sadly. I liked Error....