oh, am I happy to see this thread today! I've been working (well, was working, now taking a break to do school exams/have my boys do their school exams) on my son's comic strip quilt -- first big quilt I've done. So far I have:
-accidentally had the backing sort of fold over and get sewn over on itself at the outside edge (3 different times so far......)
-broke the Free Motion foot, not sure why (maybe not tight enough, like Nancy says?).
-tried to FMQ with a regular foot, but then I had to have the foot in the up position, which after I sewed (noticing that it was all loosey-goosey, but not sure why...), my sewing mentor told me that meant the thread wasn't on the tension thingy, and sure enough, that whole section has to be done again b/c of bunchy-ickiness on the back
-zig zag stitched my 1/4" foot to the quilt, but after reading this, thankful my 1/4" foot has a little hole over in the needle left position so at least I only sewed the foot down, didn't break the needle....
and, not on this project but on my first quilt ever I pieced the backing from 2 widths of fabric -- fabric with a semi-directional print. You guessed it, did not pay attention to that and sure enough, the 2 halves of the back go in opposite directions. ha!
Oh, and once doing an all white mini-quilt (small small, like 12" square I think it was), a single Cross & Crown block, I managed to get *one* triangle in wrong-side-out. Of course way in the center. Of course not noticed until the whole thing was together. I left it like that, as it was barely noticeable, and once quilted over it was *really* not noticeable.....
So glad I'm not alone in these!