He tweeted a potential spoiler - a photo of a coffin filled with machine guns.
"Day 20... What do you keep in your coffin?" the director wrote.
Aaron Taylor-Johnson, Christopher Mintz-Plasse, Chloë Moretz and Nicolas Cage will reprise their roles in the follow-up to the 2010 Mark Millar adaptation.
New cast members include Jim Carrey, Donald Faison, John Leguizamo and Enzo Cilenti.
A video of Carrey as Colonel Star was recently leaked online.
Kick-Ass 2 is scheduled to be released on June 28, 2013 in the US and on July 19, 2013 in the UK.
Watch the trailer for Matthew Vaughn's original Kick-Ass film below: