Initially much is made of how Howlett has to "recharge" the scalpel by killing someone. Then there are two scenes of his failing to kill someone. It's not clear if he uses the scalpel to save Jack. But later he uses the scalpel to cut through a gun, a garbage lid, and a thick metal door. It's never explained how he could use the scalpel as a super-cutting blade if he didn't charge it up.
Howlett is repeatedly referred to as Vincent. However, the name plate on his door says "Dr. M. Howlett".
Jean tries to kill Howlett, but then is strapped to a hospital bed rather than being turned over to the police.
The shop owner's last name is twice stated as "Morgan". But the end credit give his last name as "Bronson".
Although Jean is supposedly strapped to the bed and a prisoner, she asks the orderly to loosen her straps. He does so and she's instantly and completely released, with both her hands freed.