Time traveling and a certain pair of goggles.

[Riastrad]

The Echo is not time travel though at all (that instance with the pistol in the 1.0 Limsan storyline was merely a plot hole that SE appears to have since quietly ignored for the sake of consistancy), it's simply accessing and changing another's memories of an event. Us appearing in an Echo vision of when Cid defected to Eorzea to give Cid his goggles was merely a visual metaphor for us restoring his lost memories, it was a symbol of his past, and wasn't an actual event that really took place (because the Echo can also alter a person's memories to reflect that).

This is after all why SE also changed how the Echo was depicted in ARR from how it was in 1.0 where an Echo user could no longer "use it at will" but would instead randomly and uncontrollaby activate, as how it was originally shown in 1.0 where the player's character learned how to control it and use it at will (under Minfilia's urging no less!), meant it had... disturbing implications, which SE are now probably trying to get away from.

Except we did effect certain events and actively took items from the past into then present 1.0. During the 1.0 quests "Flowers for all" and Court in the Sands" we are tasked with taking a Velodyna Cosmos to the Goldsmithing (or was it Alchemist?) guild as it was a rare flower that was from then Garlean occupied territory of Ala Mhigo. We take it to the guild in question and are about to sell it to an excited merchant when the echo takes hold and we slip back into the past and sell it for a pittance as it is not "rare" in the current time. We receive said flower from the Parade in Ul'dah in the year 1562. Roughly 10 years before the setting of 1.0.

My point being that time travel was the foundation of this game. The current story seems to be going back to it as well.

A snippet from my favorite song in this game "Locus":

"Falling back right into the system of
Falling back on all that's erased
When fighting back right out of this system
Means falling back right into this space

Yes, falling back right in with the system
Who'll see you falling back to the end
When falling back is better than simply
Falling back into pieces again"

This was Alexander telling us that time is a loop. No way to change it and if you try it will only cause problems down the road, as the reason for trying to change the past is contingent on the future event taking place. Even something as simple as a flower or a pair of goggles.

I just think it's worth remembering given the state of Shadowbringers at the moment.

"Two-toned echoes tumbling through time" indeed.