That was a huge piece of the puzzle this week, but there were some other things that were really reminiscent of stories from the comics, too.
So...what did we see? What did we miss? Read on...!
Suffer a tragedy
Thawne thought that he could change Barry's destiny by making him suffer a tragedy? That sounds like a twist on the origin of Hunter Zolomon, another Reverse Flash who wanted The Flash to be "better," in that case to force him to change the past to benefit Zolomon.
Henry says that Barry might better understand things if he had kids himself.
In the comics, Barry does indeed become a father -- when he and Iris go to the future to retire, they have a pair of twins and ultimately a grandson, Bart, who would become Impulse/Kid Flash/The Flash.
Martin Stein is going to shout Stan Lee's catchphrase when he sees Barry time travel?
Back to the future
The phrase was kind of inevitable, but because the name of one of the most popular time-travel films ever made was uttered in this episode, it's worth mentioning, since otherwise that will be the first four comments below the story.
Vibrations in the universe
"You're able to see through vibrations in the universe."
Vibe is born tonight, as Wells reveals that the particle accelerator had turned Cisco into a metahuman. "A great and honorable destiny awaits you now," he says, likely hinting at Vibe's legacy as a member of the Justice League.
So long, and thanks for all the fish
Cisco name-drops one of Douglas Adams' Hitchhiker's Guide to the Galaxy books, and the phrase that the world's dolphins uttered when they left earth just ahead of its destruction in the first installment of that series.
1 minute and 52 seconds
Another one of those "52" references. Guess they're inevitable everywhere in the DC multiverse.
The wedding in this episode culminates something we've often seen in the comics -- a relationship between Killer Frost and Firestorm. In the comics, Killer Frost has often been obsessed with pursuing her nemesis romantically.
Obviously, this is far from the first time we've seen it (or acknowledged it in these columns) this year, but let's face it: if it isn't worth mentioning at the wedding, when is it worth mentioning?
Of course, the relationship in the comics was always doomed...!
May the speed force be with you
...And a Star Wars reference, too. Cisco, you're just on fire this week.
Run, Barry, run
That phrase, uttered by both Henry Allen at the time of his wife's death and by Harrison Wells during Barry's first major battle as The Flash, isn't a reference to the comics, but a
The Speed Force
Time appearing as isolated images in the Speed Force (or The Bleed, or Vanishing Point) is one of the most common ways to depict Barry accessing time travel or the multiverse in the DC Universe.
Caitlin Snow shows up as Killer Frost briefly during Barry's trip through time.
Invented by scientist, adventurer and Time Master Rip Hunter, the Time Sphere is a one-man, often single-use, time machine that is one of the most commonly-used means of piercing the timestream in the DC Universe.
Rip will be on DC's Legends of Tomorrow, the spinoff series that will also feature The Flash, Hawkgirl and a number of other DC Comics characters.
That's Rip and his father Booster Gold crashing into Barry Allen and Wally West as the four all travel through time in the image at right.
...Oh, yeah. And Rip gets a name-drop here which, if not for the fact that he had already been introduced as appearing on the spinoff, would have driven DC fans absolutely crazy.
Fans of DC Comics will recognize that metal helmet as belonging to Jay Garrick, The Flash of Earth-2. Its presence here hints at the presence of a multiverse within the world of The Flash, which opens up plenty of possibilities for future storytelling.
During that story, though, Barry did appear to Batman, The Joker and Kid Flash at various points, his speed powers seeing him vibrate briefly through time and space. Visually it was evocative of the moment here when Thawne is vibrating out of existence.
In Zero Hour: A Crisis in Time, one of a number of follow-ups to Crisis on Infinite Earths, the world is being consumed by waves of entropy, an antimatter-like event horizon caused by anomalies in the timestream. That foce looked remarkably like the singularity seen at the end of the season.
Here, we see Barry run back in time to save his mother, ultimately generating a pretty serious discussion about what such an act could do to the lives of those around him and even the fabric of reality.
It's a worthwhile conversation to have, considering that when he did the same thing in the comics, it set off the Flashpoint timeline and ultimately rebooted all of reality in the form of the New 52.
Now, that last bit was never likely to show up on the show. That said, we got plenty of hints at the big idea of Flashpoint in this week's episode.
One of the bystanders in the final scene, when citizens of Central City are looking at Flash trying to stop the singularity, was Kenda "Hawkgirl" Sunders, played by Ciara Renee.
Join us in the video above to talk about some of the Easter Eggs and get a better understanding of time travel!