I Love this topic!! I have made too many to list but here are a few. I was making a Christmas tree quilt with rows of trees. I was piecing this in rows and you guessed it, I inverted one of the rows so the bows went the wrong direction. I made a quilt with chinese lanterns and half of them had the center pieces reversed so they looked like wings. Split one of those panels of blocks apart to put some sashing between them to make the quilt bigger and did not leave a seam allowance when I cut them apart (and the panel was so old I could not replace it). I had 2 panels exctly alike that I was going to slice apart and but back together in an interesting way and I had the bottom panel turned at right angles.
We are all human -- we just have to laugh at the mistakes and go on from there.