Other mistake: Just one second after Bugs puts a letter (presumably an order for a pair of earmuffs) into a mailbox, a courier arrives with a package containing the earmuffs.
Continuity mistake: When we first see Giovanni Jones' house at the beginning of the short, there are five windows and the patio door in the middle is wide open. When Jones is frustrated with Bugs' singing and goes out to deal with him, the patio door is no longer in the middle - it is now the second door on the right.
Audio problem: When Bugs is standing by the post box and waiting for the parcel to arrive, you can hear him singing but his mouth is not moving.
Continuity mistake: When Giovanni Jones is holding a singular G note at the concert, his trousers burst and fall down to his feet. But when Bugs Bunny steps outside to order a pair of ear muffs, look at Giovanni and you can see his trousers have disappeared.
Continuity mistake: After Giovanni Jones has performed his first note during the concert's final act, you can see that Bugs Bunny's right hand is flat on his side, but in the next shot his hand is now bent backwards.
Continuity mistake: After Bugs Bunny has finished pouring the liquid alum into the sprayer, you can see the bottle of alum is still on the table but when Giovanni Jones is waiting to go on stage, the bottle is nowhere to be seen.
Suggested correction: The bottle is on the table, the spray bottle Biggs throws on to the floor out of shot.
Continuity mistake: When Bugs Bunny is sitting on the roof at the start of the concert, you can see there is nothing beside him, but just a couple of seconds later a mallet appears out of nowhere.
Continuity mistake: When Giovanni Jones is signing Bugs' autograph book with a stick of dynamite, the position of Giovanni's fingers on the book change between shots.
Revealing mistake: When Giovanni Jones performs his first note after Bugs Bunny takes over the conductor's duties, Jones's hands turn white.
Continuity mistake: Throughout the cartoon, Giovanni Jones's hair is blonde, but when he emerges from the rubble at the end of the concert, his hair is now reddish.
Continuity mistake: When we first see the concert hall at Giovanni Jones's concert, you can see that there is nothing on the left of the hall, but when Giovanni appears on the stage, a tree in a pot has appeared.