That post says about the Spielberg jab:

Now do you see what’s strange? The guy is holding a walkie talkie instead of the gun he’s seen holding in the subsequent shots of the scene (for the whole thing, head to around the 1:30 mark of the trailer).

According to Watchmen director Zack Snyder, the MPAA wouldn’t allow the gun to feature in this shot because there’s a rule against guns pointed out at the audience (in ads only).

So, Snyder claims to be referencing Steven Spielberg — I see it as a jovial attack of the filmmaker’s disappointing self-censorship — because of the 2002 re-release version of E.T.: The Extra-Terrestrial, which substituted all guns in the movie with walkies.