Continuity mistake: When Ben is lying in the bath dying, he pulls down the shower curtain covering the note he has left on the floor for the doctors. When the scene changes then changes back to him in the bath, the shower curtain's position has moved. (01:49:00)
Continuity mistake: When Will Smith goes in the car with Emily, the seat headrest is down, but just before Emily kisses Will the headrest is up.
Answer: In the course of the film it's revealed that Ben has done extensive homework and taken drastic steps to find the right person, i.e. a "righteous good person" to give them what he has left to offer. Therefore, he would have to find someone with his own rare blood type AND needed a heart...which he eventually did.
CCARNI