They include the mysterious role played by Jena Malone, whose performance was cut from the theatrical release but will be reinstated.
Snyder told EW no one had yet guessed exactly what Malone's role was.
"I think we should keep it private, but it's nothing that's been talked about. She's definitely not Robin or Batgirl. I'm happy to say that," he said.
He also admitted the film's end credits ran to almost 10 minutes.
Batman v Superman was a middling commercial success but a massive critical flop, earning just a 27 per cent approval rating on Rotten Tomatoes.
That led viewers to ask why an extended edition of the film was necessary - especially when Snyder himself has admitted: "I didn't want to make a three-hour movie."
Some even asked Snyder to make the film shorter - not longer.
The blu ray edition of Batman v Superman is due out on July 19.