Yep, the x-ray missed the squeaker Blue swallowed so they sent him home after giving him two shots (for vomiting and nausea)
We had to come back the next morning for the radiologist to read it and even he didn't see it on the x-ray.
Since we knew he swallowed the squeaker, we insisted on an ultrasound and that's where they saw it.
We got lucky, they managed to get it out via an endoscopy.
But, the vet on call that night was a total ***. He made me feel like a moron- that Blue must have pooped it out even though I knew he didn't. Like I was just being paranoid. So if she's still throwing up tomorrow, take her back and have them take the next step which I believe is an ultrasound, and make sure a radiologist reads it.
edited to add: we weren't offered a barium x-ray. i have no idea why it's not more common? the price isn't all that much more than an ultrasound.