Over the years we’ve had many movies, many tv shows, books, comics, games and so on dealing with time travel.
The most recent of note is Continuum.

So someone travels back from the future, they take technology in to the past, and then they change things.
Depending on what and how they change thing determines if the technology of the future changes or even exists.
Just by being there and used as a sample it may accelerate and enhance development, which of course by it’s nature changes the subsequent iterations leading up to the seed tech in the future.
By it’s very nature improving the technology in the past with technology from the future changes that very technology in essence.

The beginning of this has been covered in Continuum with HALO incorporating future elements.
By it’s very nature, all the technology based on HALO from then on will have different future iterations, unless you posit that the path to the end journey doesn’t change as much due to the level of science required to analyse things is insufficient to do more than provide a road-map.

This of course starts falling apart when you start including multiple alternate future timeline technologies.

Liber8 travel back to the present to prevent the corporate congress from forming and thus if they succeed they lead to a temporal paradox, their very history no longer exists.
Kiera travels back by accident (or the intention of Alec Sadler) and seeks to prevent Liber8 from accomplishing their goals.
Sadler sends information back via Kiera (unknown to her) for himself as a way to change his future.
Sadler sends Garza back again for his own goals, muddying Liber8’s purpose.

That’s just the first batch from the exact time period, it doesn’t even include Freelancers.

At the end of last season Alec traveled back two weeks to change the past and save someone from death, resulting in two Alec Sadlers, two time travel devices, and two timelines, of which one ceases to exist.
Kiera travels back as well, resulting in two Kieras, two CMRs, two suits and so on.
Things start escalating quite dramatically from there but technologies don’t change too radically.

The problem is from there a third timeline spawns leading to Brad being sent back.
His technology is completely different to the other two timelines.
His very being there invalidates all the other tech that has traveled back, possibly even the very method of traveling back.
And yet the other tech does not cease to exist.

The only way this works is if the multiple timelines co-exist, with the path taken being determined at key junctures but the potential to cross between them.

Whatever happens, Continuum is handling such things interestingly.
I look forward to seeing where they go from here with the advent of the Bradpocalypse timeline.
It’s just going to get even more messy and lead to some great character development.

AmK