Declan Mulqueen: This man is no clown. He knows all your moves, back to front. Right now you've got a name; that's all you've got. The Jackal has got a target: you. He's got a timetable. And as to making mistakes, he's spent twenty years in a trade that doesn't forgive error. And he's prevailed. You think he's the one up against it? It's the other way around.
When the Jackal shoots Lamont, only the lower arm is shot off. Then we cut to the Jackal, who says 'I told you it was off', and when we cut back to Lamont, the arm is cut way up at the shoulder.
The scene in which the Jackal kills Douglas was re-shot at Bruce Willis' request. He wanted to show that Douglas was killed because he knew too much about the Jackal's identity, instead of simply because he was gay.