IN PHOTO: Cast Member Grant Gustin Attends A Panel For The CW Television Series 'The Flash.'
IN PHOTO: Cast member Grant Gustin attends a panel for The CW television series "The Flash" during the Television Critics Association Cable Summer Press Tour in Beverly Hills, California July 18, 2014. MARIO ANZUONI/Reuters

"The Flash" premieres in under three weeks on The CW. Barry Allen, portrayed by Grant Gustin, has appeared on "Arrow," which is opening its third season in the same week. Here are ten things to know about this new adaptation of another popular DC Comics character.

The Flash 2014 on The CW, 10 Things To Know Featuring Some 'Arrow Connections'

Here is a round-up of scoop and information from various entertainment reports:

10. The actor playing Barry Allen played a bad guy in the FOX comedy, "Glee." Grant Gustin's Sebastian Smythe is the lead singer of the Dalton Academy Warblers in Season 3.

9. Barry Allen appeared in two episodes in Arrow Season 2. In Episode 8 ("The Scientist"), he quickly establishes a connection with Felicity Smoak (Emily Bett Rickards). In Episode 9 ("Three Ghosts"), he gives Oliver Queen (Stephen Amell) a new mask as a farewell present.

8. Oliver Queen, aka The Arrow of Starling City, will appear in the pilot episode of The Flash.

7. Rickards' Felicity would show up in Episode 4 of The Flash.

6. Fans will enjoy two crossover episodes featuring Arrow and The Flash. Each show's Episode 8 will have both Barry Allen and Oliver Queen.

5. John Wesley Shipp, who played The Flash in the 90s on CBS, is playing Henry Allen, Barry's father on The CW.

4. Robbie Amell, cousin of Stephen Amell and a lead actor in the cancelled series "The Tomorrow People," is playing the role of Ronnie Raymond. In DC Comics, Ronnie is one half of Firestorm.

3. The CW has posted "In A Flash Trailer" on YouTube. Watch the clip below, or follow this link. Tom Cavanagh, who plays Dr. Harrison Wells in The Flash, makes a significant presence in the trailer.

2. Greg Berlanti and Andrew Kreisberg, who developed "Arrow" together (with Marc Guggenheim), are joined by Geoff Johns in developing The Flash.

WATCH: The Flash Trailer | The CW on YouTube | 'Run, Barry, Run!'

1. The Flash premieres Oct. 7 on The CW. The Arrow Season 3 premiere air date falls on the next day.

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