Continuity mistake: When Constantine gets the cigarette box he slides it across the table. Later there is a close-up of the cigarette box and we can see it has moved closer to the edge of the table. (00:17:50 - 00:19:00)
Continuity mistake: At the end of the film when Lucifer has ripped open Constantine's shirt and removed tar, immediately after when he goes back to Angela, the shirt is suddenly done up again. (01:44:35)
Continuity mistake: In the end when Constantine slits his wrists there is a shot where you see the pools of blood from his wrists. The scene changes for a few minutes and there is another shot where the blood is visible and the pools are smaller than before. If anything they should have been bigger. (01:35:20 - 01:40:50)
Continuity mistake: When Constantine submerges Angela in to the tub he pulls up his right arm from her head. When it cuts to a shot under water he pulls up his arm again. (01:04:00)
Continuity mistake: When Constantine has a sip from his cough medicine, we see the Vermin Man approaching him in the background. A few shots later we see the Vermin Man is still approaching him but he is still moving in the same spot as earlier. (00:26:25)
Continuity mistake: When Constantine is heading for Midnite's office, he stops by his door. A man opens the door and walks out passing Constantine. At that time you can see the background is full of people. When it cuts to Constantine walking in the door the background has changed, the people are gone and a blue wall has appeared instead. (00:29:35)
Continuity mistake: In the X-ray room when Constantine has lowered his cigarette he is standing next to Les and walks away. Their conversation goes on for a couple of shots and then suddenly he is standing right next to Les again and walks away. (00:14:15)
Continuity mistake: At the end (after the credits), when Constantine place the lighter on Chas' grave, Constantine's fingers on the lighter change position in the close-up view. (01:54:50)
Revealing mistake: When it's raining a lot and John is taking a cough suppressant, he sees some kind of bird fly by and looks up. There's a shot of his face from above and the rain is falling around him but not on his face. (00:26:40)
Continuity mistake: When Angela is standing in front of the elevator and Constantine asks her what's wrong his hand is not on her shoulder. When it cuts his hand is on her shoulder right before she gets dragged through the wall. (01:14:45)
Continuity mistake: When Angela walks out of the confession box she grabs her necklace cross and holds it. When it cuts from behind her, both her hands are down. (00:11:15)
Factual error: When Angela talks to a priest about giving Isabel a Catholic funeral, the priest says that it's impossible because Isabel committed suicide. Even though the church does consider suicide a mortal sin, this rule doesn't apply to people who have a history of mental illness.
Continuity mistake: In the beginning when the Mexican's foot goes through the planks under the sand, a lot of dust comes up. When it cuts from within the hole we can see through it and the amount of dust has decreased. (00:01:00)
Continuity mistake: When the demon manages to break through the mirror it's stuck in, its hand comes through the mirror. When it cuts its hand is nowhere in sight. (00:08:10)
Continuity mistake: When Constantine knocks out the bouncer at Midnite's the bouncer's arms change position between shots. (01:15:25)
Continuity mistake: When Constantine and Chas are heading for Midnite's the first time and Constantine says "You're reading too much, kid. It's a bar", you see Constantine walking with his hands down. When it cuts, he's holding his cigarette to his mouth. (00:28:05)
Continuity mistake: When the Mexican walks away his friends talks to him while crouching. When it cuts we see his friend in the background but now he is on his knees. (00:01:50)
Continuity mistake: When the Mexican wraps up the Spear of Destiny he places the Nazi flag with the swastika pointing up. A couple of shots later when the Mexican turns around, the flag is folded in a different way and the Swastika is not visible. (00:01:35)
Continuity mistake: When Constantine approaches the apartments where the possessed girl is, he meets a woman holding a man while walking in front of him. When it cuts the woman is still holding the man, but now she is behind him. (00:04:20)
Continuity mistake: When the possessed girl talks to Constantine she has a big lump of hair on her forehead. When it cuts there is no trace of hair on her forehead. (00:05:25)
Answer: Sin for a good reason is still sin, and as Gabriel says earlier, you can't buy your way into Heaven. Real Catholic dogma, however, doesn't hold the mentally ill as condemned for committing suicide.
Greg Dwyer
Except Isabel wasn't mentally ill. She saw angels and demons just like Constantine did. It was her parents who believed she was mentally ill.
While suicide is a mortal sin, it's shown later (as in major plot point) that sacrificing yourself to save the world is a redeeming act.
Yes, but Constantine also said "My parents were normal. They did what most parents would do. They made it worse. You think you're crazy long enough, you find a way out" which could relate to Isabel losing her sanity in a way as well because of her family and how they saw her. The whole Isabel's sacrifice is added by the novelization but the movie is ambiguous about the suicide.
mp1920
Except Isabel wasn't mentally ill. She saw half breeds just like John did.
Sacrificing yourself for others isn't a sin.