Some pages of the Journals are possibly blood splattered, particularly the ones with Bill Cipher.
A gnome latches on to Dipper's face, and Mabel punches it several times to get it off, inadvertently hurting Dipper in the process. His eyes become purple and is visibly dazed.
In the episode "Headhunters", a wax figure modeled after Stan is decapitated. Various other wax figures are dismembered or decapitated in the episode.
In the episode "Summerween", a monster eats a little kid, and later eats Soos.. Some children attack a monster with swords, sickles and axes. The kid who was eaten before comes out alive. The monster reveals he is made of candy, and then Soos bursts out of its chest and eats its heart, played for laughs, but can still be unsettling.
Otherwise, Stan tries to scare some kids by taking what appears to be sausages out of his stomach (shirt) surrounded by ketchup, intended to look like intestines.
During the climax scene in "Gideon Rises", after Dipper is thrown out of Gideon's machine, we see a small amount of blood coming out from his nose. Also in this episode, Gideon and Dipper fight by punching and slapping.
In "Scary-oke", Soos gets bitten by the zombies and a wound is seen on his shoulder. Stan and the twins kill some of the zombies, rather graphically. They are dismembered, crushed, beaten, and even cut in half, albeit with green blood. Later on, their heads explode, splashing more green blood.
In "Into the Bunker", there is some fighting with Wendy and the Morph Monster and she receives an injury on her leg. The monster impersonates Wendy, and Dipper thrusts an axe into its abdomen, giving the appearance of Wendy with an axe stuck in her, though with green blood.
At the ending of "Society of the Blind Eye," a metal bar hits Stan's hand and a large bloody wound appears. He puts a bandage on and the blood can be seen soaking through it.
In "Northwest Mansion Noir", there is a scene where animal heads on walls start chanting "ancient sins" and then have blood ooze out of their eyes and mouth.
In the same episode, in a flashback, we see the ghost, when he was alive, gets stuck in a mudslide and his axe hits him leading to his death. We don't see the actual impact, however we do see his ghost with an axe stuck in his head.
In an episode with Bill Cipher, Bill gives Dipper "a head that's always screaming." The screaming head disappears after its skin and muscles peel off revealing its skull.
In "Sock Opera," Bill possesses Dipper's body and proceeds to hurt himself by throwing himself down the stairs and repeatedly slamming his arm in a drawer. When he takes his arm out of the drawer, there are forks sticking out of it.