In the first episode, Kenshin walks in on Kaoru bathing, mistakenly believing she's attempting suicide. He looks at her naked body accidentally, though nothing is seen. Played for laughs

In one episode, Kenshin walks up to Kaoru and Megumi in a hot springs naked (though he himself doesn't know he's naked). Nothing whatsoever is seen, but the characters reactions make it obvious and Megumi makes a somewhat lewd comment to him. Played for laughs.

In one episode, Yutaro walks in on Yahiko about to take a bath. Objects around the room conveniently cover most nudity on Yahiko, but his buttocks are very briefly seen. This scene is played for laughs.

There's a guy in a tree looking at the girls bathing in a scene done later in the show

Some episodes shave mild sexual references but no nudity.

Four men are shot to death and one is shot repeatedly in both legs, plenty of blood sprays and stains the ground, though the actual act is mostly shadowed out.

The first half of season one has mostly bloodless or offscreen violence, but later episodes have some blood.

A violent fight scene that goes on for a couple episodes in which several swordsmen fight several army officers. During this, several men are shot to death with plenty of blood spraying (though it's mostly seen in still-shots) and several others are slashed with swords.

One episode has several men killed by several others with swords. Although mostly in still-shots, plenty of blood sprays in a couple instances and the very bloody aftermath is seen.

A woman is shot in the leg. Plenty of blood sprays and the wound is graphically seen afterwards. A man then takes the bullet out of the wound with a knife, though this is offscreen.

Bloodless samurai martial arts violence in general, though it becomes more violent in the Kyoto arc.

Some blood is seen for comic effect. (Example: Kenshin accidentally getting his thumb caught in the sheath of his Katana.)

The middle finger is used in a few episodes.

Some mild swearing (Damn, hell etc.)

It's stated that a man died from Opium overdose and that one character was forced to manufacture it.

In one episode, Yahiko (a young boy) drinks an entire bottle of Sake and ends up getting dizzy and passing out from intoxication.

One episode is about Opium.

The battle scenes might frighten some. The Kyoto arc also has some violently intense moments (involving Shishio).