Looney Tunes: The Golden Collection --- 4 DVD Set! --- Available NOW!

"Martian Through Georgia" (Jones and Levitow; 1962):

ABC: After the Martian runs around a hellish setting in a panicky state, he considers suicide, pointing his space gun to his head. The narrator says, "Commit suicide? Why not? If nobody loves you." Such contemplation of suicide is invariably considered unsuitable for broadcast.
CN: Same edit as on ABC. The visual of the Martian putting his spacegun to his head is replaced with a frozen shot of the Martian holding his ears.
Nickelodeon: Same edit as on ABC.
WB: Same edit as on ABC.

"Mexican Boarders" (Freleng; 1962):

Nickelodeon: Sylvester sloppily downing a bottle's content of pep pills as the narrator introduces Sylvester, calling him, "The most pooped cat of all Mexico because he was chasing the fastest mouse of all Mexico," was eliminated either by an editing of both picture and sound or by retaining the sound and thus the narrator's description of Sylvester with a still shot of Sylvester laying on the floor superimposed over the censored act.

"Mexican Joyride" (Davis; 1947):

TNT: All shots of the bull holding a gun against his head were removed, rendering the scene of Daffy nearly duping the bull into killing himself difficult to comprehend.

"Mississippi Hare" (Jones; 1949):

ABC: The "Camptown Races" song, with Colonel Shuffle in blackface after Bugs provided to him an exploding cigar and playing a banjo, was censored on ABC in the cartoon proper but did appear as a "Comedy Classics" clip on Bugs & Tweety in the 1989-90 season. Also deleted from this cartoon: the explosion in Colonel Shuffle's face after he checks to see if his gun is full of water following Bugs' warning to that effect, and some of Bugs as the Southern belle hitting Shuffle with his/her umbrella.
WB: The entire section of the black cotton pickers singing "I Wish I Were in Dixie" was gone, and so too was the aforementioned gunshot into the visage of Shuffle.

"Mother Was a Rooster" (McKimson; 1962):

CBS: Several punches between Foghorn and the barnyard dog during the boxing ring scene were cut out of this cartoon.

"Mouse and Garden" (Freleng; 1960):

ABC: Edited out of this cartoon was Sam the Cat replacing the captured mouse under Sylvester's foot with a stick of dynamite, Sylvester swallowing the dynamite, and the requisite explosion, with Sam then saying to the unwell-looking Sylvester, "You'd better have that tooth fixed."
Nickelodeon: Sometimes missing was two lines of dialogue: Sylvester's question, "You never know where those little devils will hide do you?" and Sam's lament, "Now you made me feel b-a-a-a-d!"

"A Mouse Divided" (Freleng; 1953):

ABC: The entire opening sequence featuring the drunken stork leaving a bar in the clouds and his being too inebriated to complete his assigned task to deliver a baby mouse to parent mice, was omitted, hence obscuring the explanation of how Mr. and Mrs. Sylvester came to be father and mother to an infant rodent.

"The Mouse-Merized Cat" (McKimson; 1946):

CN, WB: Eliminated from this cartoon was Babbit hypnotizing Catstello to act like Rochester receiving a telephone call from Jack Benny.

"Mouse-Taken Identity" (McKimson; 1957):

ABC: The scene wherein Sylvester Jr. "rescues" his father from being eaten by a stuffed lion's head by shooting a gun at it and thence into Sylvester's backside, was gone. Also unseen was Hippety Hopper in Indian garb and scalping Sylvester.
Nickelodeon: The aforementioned lion's head and gun scene was edited out of this cartoon.

"Mouse Warming" (Jones; 1952):

ABC: Claude Cat posts a sign reading "borders welcome" on the door to the home of the female mouse and her father, thereby enticing a youthful, male rodent who is in love with the female mouse to come to their home seeking lodging. Claude next forges and sends a letter to the father mouse to impersonate the infatuated, young male mouse, with a statement to the effect that he (young, male mouse) found their home first and plans to move into it, thus raising the ire of the father mouse, who obtains his gun. All of this is Claude's attempt to lure the young, male mouse into the open so that said mouse can be captured. However, Claude receives in his face the blast from the father mouse's pistol, and the young, male mouse scurries back to his own bachelor rodent apartment. This was gone. Also missing was Claude licking his face after it had been slammed by a garbage pail lid moved by the male mouse in a prior scene.
Merrie Melodies: Father mouse fires the gun into Claude's face. At the moment of gunshot, a still frame of the father mouse's daughter looking out of a window was shown instead of the act of violence, which was only heard.

"Mouse Wreckers" (Jones; 1949):

ABC: The scene wherein one of the mice hits Claude on the head was deleted, the angered bulldog pounding Claude was shortened, and the scene of the mice sneaking a lit dynamite stick into Claude's pillow, with Claude being caught in the explosion and then anxiously drinking his nerve tonic as though it were soda pop, was fully censored.
CBS: Hubie and Bertie string a rope so that a boulder pushed down the house's chimney will send Claude careening all through the house. CBS showed the path of the rope, heightening audience anticipation. Alas, once the trap is triggered, viewers only saw the end result: Claude smashing into some kind of shield, completely flattening him. Moreover, this cartoon was cut to end before the final shot, of the mice triumphantly toasting marshmallows in the opened fireplace.
Merrie Melodies: Claude's ordeal with the bulldog was trimmed to reduce the violence.

"Muchos Locos" (McKimson; 1966):

CBS: The flashback from "China Jones", in which Daffy encounters the "dragon lady", was cut so that while she breathes fire on him, the result was not shown.

"Muscle Tussle" (McKimson; 1953):

ABC: The muscular duck punching Daffy's head into Daffy's shirt was omitted from this cartoon.

"Music Mice-Tro" (Larriva; 1967):

CBS: Daffy falls into a swimming pool and is then zapped by a sunlamp's electric current, but CBS spliced Daffy's electric shock out of this cartoon.

"Mutiny On the Bunny" (Freleng; 1950):

ABC: Gone was a short shot of Shanghai (Yosemite) Sam pointing a pistol into Bugs' face.

"A Mutt in a Rut" (McKimson; 1959):

ABC: This cartoon was edited to lack the scene wherein Rover uproots a sign that says, "Danger: Blasting," then buries dynamite into the ground. Fudd walks onto this site, and Rover presses downward on the dynamite detonator, but the dynamite does not explode. So, Rover shoves Fudd aside and realizes that he forgot to connect two wires; Rover connects them, and the dynamite explodes on Rover!
CBS: Gone was a scene in which Rover fires a gun at Elmer but accidentally instead kills a bear, appearing to save Fudd's life.

"Muzzle Tough" (Freleng; 1954):

ABC: Scenes affected by censorship of violence were Granny shooting a gun at Sylvester, who is beneath a bear skin, and Tweety sticking the tail of Sylvester, who is disguised as a lamp (his tail therefore seeming to be the lamp's electrical wire), into a power socket, severely shocking Sylvester with electricity, and the bulldog then biting Sylvester's tail and, too, receiving a jolt of energy.

"My Bunny Lies Over the Sea" (Jones; 1948):

CBS: McCrory shoots his rifle at Bugs, but the CBS censors removed the scene of the bullet stopping in motion, McCrory grabbing it, and saying that it has been in his family for years.

"My Little Duckaroo" (Jones; 1954):

ABC: The scene wherein Nasty Canasta rolls a cigarette with his tongue is gone. Also missing were Daffy disguising himself as "The Fre-e-esco Kid" ("Come along quietly we-e-eth me, Senor, or I we-e-ell whe-e-ep you!"), Canasta sticking a gun down Daffy's throat while they play cards, Daffy mistakenly shooting himself with his own gun, and Canasta delivering a punch into Daffy's face.