Yes, it happens...way too often...patterns should be tested, and retested for accuracy before they are published, but they must not always be.
I had a problem with the border on a pattern from a popular designer. I could not get it to work out without taking in every seam. After I was done, and frustrated, I did the math from the center of the quilt, to the border. It was oiff by 2"...no wonder I couldn't get it to work out. I wrote to the designer, and got an apology, and a free pattern.
If the pattern is in a book, sometimes it is caught quickly, and a sheet of errors is included in the book. Most designers also will have a page with errors on their websites.
The worst are patterns in magazines...always make a test block for those, and at each step of quilt after, I do the math to make sure the next part of the quilt will fit.