Incorrect way of drawing a curly arrow:

In some books, you may see the arrow written directly to the proton shown in the below diagram. Basically, this is not correct. Arrows should just only be drawn directly to an atom if the electrons are going to end up on that atom like a lone pair of electrons.

Figure:   Incorrect way of drawing a curly arrow.

The subsequent rules are worth remembering while drawing arrows:

1. Curly arrows depict the movement of electrons, not atoms;

2. Curly arrows begin from the source of two electrons (that is a lone pair of electrons on an atom or the middle of a bond that is about to be broken);

3. Curly arrows point to an atom if the electrons are going to end up like a lone pair on that atom;

4. Curly arrows point to where a new bond will be created if the electrons are being employed to form a new bond.