The Last Giant, a boss enemy in the Forest of Fallen Giants, has a semi-rare instant-kill move during the second part of its fight where it simply tries to fall and crush the player with its body. If the giant is killed while it is still laying flat on the ground, a unique death animation will play where it lifts its upper-half up to wail before dying.

Inside the abandoned chapel in Brightstone Cove Tseldora, in the middle of the first room is a group of mushrooms. Hidden underneath them is a Pickaxe which can be used as a weapon, though isn't a particularly good weapon given the effort needed to uncover it. To get it, the player must aggro at least one Undead Boar at the Royal Army Campsite and then very carefully lead/push it all the way down to the chapel until it finds the mushrooms and proceeds to them dig up.
It is also possible to get a friendly piglet from the Royal Army Campsite to follow the player, but they only have a 1/1000 chance of spawning.

Blacksmith Lenigrast has a very similar appearance of the Burrow King from one of the archstones in From Software's first souls game Demon's Souls.

If the player has obtained the Giant's Kinship before defeating the Throne Watcher and Defender, Nashandra will enter the room through a fog door and the fight will begin.

There is unused dialogue in the game's files of Gavlan speaking an unknown language. This is likely the language of his people, the Gyrm.

The world map of Dark Souls II has several locations that overlap if all the maps are loaded at once. Notable examples would be the Shaded Woods, Aldia's Keep, and Drangleic Castle all occupying the same spot, Door of Pharros somehow at a higher elevation than Drangleic Castle despite Door of Pharros being underground and the castle above ground, and Iron Keep being set above Earthen Peak despite that Iron Peak is a castle surrounded by lava which is somehow above Earthen Peak's windmill.

There is concept art for a child model of the Emerald Herald in the game's files, however there is no dialogue to reveal what purpose it would have served.

In the Grave of Saint, after releasing a pool of acid using a Pherros Lock Stone, it is possible to see a Heineken beer can in the pool's texture.

In the DLC, if the player defeats the Sir Alonne boss fight within 5 minutes and takes no damage, Alonne's death animation will show him committing sepukku.

In early concept art Lucatiel of Mirrah is shown using a thrusting sword as a weapon, but in the release version of the game she uses a greatsword and shield.