Both posters say: "Cities Fall."
Both posters use "Rise;" Deep Impact says "Oceans" while Dark Knight Rises says "Heroes." A "hero rising out of the ocean" would nearly be the same thing as a "beast rising out of the sea" (Revelations 13:1) as the antichrist will be perceived as a "hero" (on a white horse.)
Deep Impact poster says Hope Survives. I have shown in the past that Hope refers not only to current U.S. President Obama but to an ELP (earth-like Planet - the ELP with Arthurian overtones.)
In the Dark Knight Rises poster, the people look to be not happy, perhaps rioting and the clock clearly shows that it's 11:11 in 2012.
Although not accurate (the Navy website changed the Mayan calendar "doom time" to 11:12 in 2009) the 11:11 time still stands in the minds of most people.
The Dark Knight Rises poster also clearly shows two darkened towers:
Which if nothing else would remind one of 911. The 11:11 clock between the two towers let's us know that "time is up" and the "Cities Fall" mantra (along with the other slogans) clearly send a 911/apocalyptic message: Two towers, 11:11. Emergency. 911.
While Deep Impact sends a natural disaster message, the Dark Knight Rises clearly send another message altogether. A hero is coming to save the world (the bat at the top the building has risen from the grave - dead from a head wound - as we have seen in another poster.)
CLEARLY, the Dark Knight Rises is at least the mini-story of Quetzalcoatl, King Arthur, Jesus and/or the antichrist.