- Wolverine popping his claws out through his knuckles must be even more painful than it looks due to his Healing Factor which would likely prevent scar tissue from forming. Every time he does it it's like he's doing it for the first time.
- John Howlett was a mutant. Elizabeth Howlett has clearly been clawed, and when James sprouts claws she's all "not you too". But he must have lacked the healing factor, seeing as he stayed dead after his mother killed him, probably in self-defence.