'Avengers 4' had its wrap party Thursday and the centerpiece was a giant Thanos cake, but it's what was underneath the franchise's evil villain that could give away who survives in the flick.

Look closely ... you'll see 4 arms holding up the platform on which Thanos is standing. They appear to be the arms of Black Widow (Scarlett Johansson), Vision (Paul Bettany), Black Panther (Chadwick Boseman) and the Hulk (Mark Ruffalo). Pay attention to the fingernails, claws and colors of the suits.

Marvel execs have hinted some of the superheroes wouldn't make it past "Avengers: Infinity War," which hits theaters in May, and this 'Avengers' film won't see the box office til 2019, so a lot can happen.

The burning question ... do the 4 conquer Thanos, or are they the ones who succumb to his evil powers? Some 'Avengers' fans believe Captain America doesn't make it, and if that's the case the 4 here would be Thanos' worst nightmare.