Batman is Kirk Langstrom instead of Bruce Wayne. In the comics Langstrom is Man-Bat, one of The Batman's many enemies. The film sees a play on him being less of an actual man size bat and more of a classic horror vampire.
The affiliated scientists to the Fair Play Project are: John Henry Irons (a.k.a. Steel), T.O. Morrow (member of the Injustice League), Michael Holt (a.k.a. Mister Terrific), Victor Fries (a.k.a. Mr. Freeze), Pat Dugan (a.k.a. S.T.R.I.P.E.), Emil Hamilton (member of the Secret Society), Karen Beecher (a.k.a. Bumblebee), Ray Palmer (Atom), Silas Stone (father of Victor Stone a.k.a. Cyborg), Thaddeus Sivana (a.k.a. Doctor Sivana, member of the Injustice League), Kimyo Hoshi (a.k.a. Doctor Light), Stephen Shin (ocasional friend of Aquaman) and William Magnus.
Wonder Woman in this film is named "Bekka". In the main DC continuity, she is a minor character and Orion's wife.
According to writer Bruce Timm, the hardest character to redesign and reimagine was Wonder Woman. It wasn't until after bringing up an old sketch that inspiration struck.
Batman who "only kills criminals" is voiced by Michael C. Hall who portrayed Dexter Morgan a serial killer who only killed serial killers.