Nope, it's not your picture of "the best duck confit I've ever had" that's causing that Twitter post to error out -- the service is down for "some users," according to a Twitter status page update. It's unknown what's causing the issue (again, probably not your photweet), but we're assured "engineers are currently working on this issue." We're experiencing some snags ourselves, usually resulting in tweets timing out before publishing. Hang tight!
But maybe don't try to while away your time on the iTunes Store or by backing up your phone to iCloud, as those services are also experiencing some downtime issues this morning. An Apple support page lists both as seeing "some users affected;" we'll just have to assume engineers are also hard at work on fixing that. As always, we'll let you know when things get better.
Update: Looks like Twitter is all back to normal, and the company says, "this issue has been resolved." Apple, on the other hand, is still having issues with Apple ID and Game Center login.
Update 2: Apple is now all back to normal as well, according to the company's support page. But do let us know if you're experiencing any issues!