Some interesting findings happen in this episode. And there are some happenings which are brought back from previous seasons. But because of Crisis, all can be new (and old) for some characters.
New to the Old:
The Pied Piper is back in Central City. Not only is he back to robbing stores, but also has a new trait which helps him get away. When Barry goes after him, he finds Central City itself has also changed with Crisis. He also can’t find the cemetery where his parents are when he tries to make a visit.

Gideon has been expanded to the rest of STAR Labs than just being in the secret room. She has been helping Barry in making devices while Cisco has been gone.
Frost and Caitlin seem to have meshed their minds together. In the past, when there was a scientific problem or situation to be solved, Frost would let Caitlin take over to help solve it. Now, Frost is doing the brainy work.

Grodd seems to be a good guy now. He takes over Barry’s mind to ask for his help in defeating the Gatekeeper Solovar. The same Solovar Barry had to defeat no thanks to the help of Grodd on Gorilla World.
New team member to Team Flash: Chester. (Yes, the person who opened the black hole. And the team does remember that. They mention it.)
The “old” villain to join the new Central City: Eobard Thawne or Reverse Flash!

The Flash episode 14: “Death of the Speed Force” with the return of Wally West!