I'm seeing items like "The many pained expressions of Chris Christie standing behind Donald Trump."
Lots of commentary, including lots of mockery. Of course, there's always mockery whenever anything Donald-Trump-related happens, so there's no way to avoid mockery. But, still, why stand there like that?
To me, Christie looked like some sort of body-guard or enforcer, so I'm going to suggest that was the intended message. That is Christie's role in the Trump campaign. Look for more of it. Haters may react: But Christie looked ridiculous! And my response to that would be: Trump has kept you off guard all this time by provoking your ridicule. It's how you are disarmed.