Brief nudity.

Many acts of graphic violence (gunshots, hand-to-hand combat and dismemberment), particularly one graphic shot in the first episode where a woman's brains are shot out.

Strong profanity in the English dub. At least 140 uses of 'fuck'.

Much, much less in the original Japanese.

Some smoking.

Lots of horrific violence including torture. Although the pervasive amorality that saturates the show is greatly lessened later on.

On a lower note, the original Japanese version had Anti Semitic themes. but both the Manga Entertainment dub and subtitles are censored to cover this.