The Flash becomes the first Arrowverse series to acknowledge the canceled Arrow spinoff, Green Arrow and the Canaries. When Arrow was getting ready to come to an end, the eighth and final season tried to set up one more spinoff before Oliver Queen's time on The CW concluded. Even though the first Green Arrow was now dead after Crisis on Infinite Earths, that didn't mean the mantle wouldn't get picked up. The penultimate episode of Arrow served as a backdoor pilot for his daughter Mia Queen along with the two Black Canaries, Laurel Lance and Dinah Drake.
Green Arrow and the Canaries would have followed the new Emerald Archer and the Black Canaries in Star City 2040. The backdoor pilot has Laurel going to the future to restore Mia's memories as she didn't remember her life pre-Crisis. But another mystery was also set up with Dinah somehow finding herself in the future the day after Oliver's funeral. A mystery villain was also put in place that was restoring other characters' pre-Crisis memories. Unfortunately, The CW ended up passing on Green Arrow and the Canaries, meaning it didn't join the Arrowverse slate.
Since the cancelation of the Arrow spinoff, the other Arrowverse shows have barely acknowledged Green Arrow and the Canaries, mostly because it does take place in the future. However, The Flash season 7 became the first one to not only bring it back but also set up its own connection to the scrapped series. When Abra Kadabra shows up in the year 2021, he's revealed to have a Martian Memory Restorer, the same tool Laurel and the 2040-baddie were using in the backdoor pilot. But while it's connected to Martian Manhunter's power on Supergirl, it's also revealed that Cisco Ramon was the one to design the actual restorer.
During that moment in STAR Labs, the team wonders why Cisco had even made it in the first place. An annoyed Cisco begins to explain why by referencing Laurel Lance and Mia Queen before cutting himself off, knowing that this was a long story for another time. What this seems to confirm is that before Laurel went into the future, she got it from Cisco who seems to be in the know of why Black Canary had to take off. Perhaps The Flash season 7 will continue to bring up the fallen spinoff or perhaps be the show that gets to resolve it.
It's still a shame that Green Arrow and the Canaries didn't go forward as the backdoor pilot did set up a huge plot for those characters. The CW should still consider finding ways to wrap it up whether it's as a digital comic, an arc on Legends of Tomorrow, or other ways. While those characters may not continue on a weekly basis, it still would be helpful if the other Arrowverse shows could find a way to bring them back for a limited arc. Since Arrow season 8 did a lot of groundwork for the spinoff, particularly with Mia taking over as Green Arrow, it would be great if a show like The Flash could give Green Arrow and the Canaries a worthy conclusion.