8. Sylvester Stallone Wears His Judge Dredd Uniform
The Rumour: It's been long-known that Sylvester Stallone makes a cameo appearance in the film, and the word on the street is that his appearance as Ravager Stakar Ogord (aka Starhawk) sees him don his iconic Judge Dredd uniform from the controversial 1995 movie.
How Likely Is It?: This sounds exactly like something James Gunn would do, given his affinity for nerdy pop-culture references, and it'd be an hilariously self-aware way for Stallone to rib his own prior involvement with a comic book property.
Don't take it as a given in case it doesn't in fact happen, but this just makes way too much sense not to probably be true. 8/10