In the comics it was Batman's enemy Ra's al Ghul that got ahold of Batman's secret files regarding his Justice League teammates and their weaknesses instead of Vandal Savage.
Phil Morris reprises the role of Vandal Savage from Justice League (2001). Morris also played John Jones aka The Martian Manhunter on the television series Smallville (2001).
Kevin Conroy (Batman), Tim Daly (Superman), Susan Eisenberg (Wonder Woman), Carl Lumbly (Martian Manhunter), Phil Morris, Olivia d'Abo (Star Sapphire), and Alexis Denisof all reprise their previous television roles for this film. Additionally, Michael Rosenbaum, who previously voiced Flash Wally West, returns to voice Flash Barry Allen.
In the original comic book storyline Wally West was serving as the Flash instead of Barry Allen. This was due to Barry Allen being lost in the Speed Force at the time and he did not officially return until 2008, which was 23 years after he was originally killed off.