Stephen C. Carlson lists three errata in Swanson’s collation of P46 in Galatians based on his careful perusal of the University of Michigan images.
Swanson, Reuben., ed. New Testament Greek Manuscripts: Variant Readings Arranged in Horizontal Lines Against Codex Vaticanus. Galatians. Wheaton: Tyndale House, 1999. 0842339744, 978-0842339742. William Carey, 2002. 0865850690, 9780865850699.
You can also check out my post referring to the background of how Swanson compiled these volumes.