Flagging spoilers.

Goofs can be flagged as containing spoilers, although I believe IMDb intends this only to be used for major ones. If you read the goofs before seeing the movie you may run into minor spoilers.

The Submission Guide: Goofs states :

7. Please try not to include anything that reveals key elements of the plot at all, but if you can't avoid it, begin your item with:

SPOILER:

This tag will then be recognized by the database and automatically placed beneath a SPOILERS! warning, so that anyone who does not wish to know what happens can avoid reading it.

For quotes, IMDb's stated position is that if you read the quotes, you have to expect there will be spoilers. If you are worried about spoilers, don't read the quotes before seeing the the film.

Occasionally, some contributors will enter a [spoiler] tag as the first line of the quote, but this is seldom done and even if it is, it does not reposition the quote.

Well, I wasn't reading goofs. As I said; "so that the information in question doesn't appear on the movie main page". You know, where it always includes one item from each page.

And I don't see any easy click link to flag anything as a spoiler, but I'm not a pro member.