Random slot/field publishing error

I have attached a screenshot of a publishing error that recently occurred on our production server. I have never seen this error before and it apparently only lasted for one publishing cycle after the content type had been updated. I think this was the result of a publishing error since I do not see a way to reproduce the error in order to prevent it from occurring in the future.

As you can see from the screenshot, some of the slots were not processed during publishing, instead some sort of field/slot macro was displayed. The order in which the references appear on the screen is the same order they are referenced within the template source code.

Hopefully I won’t see this error again.