Continuity mistake: After Jerry has finished eating Tom's breakfast, he jumps on the butter knife and the butter hits Tom in the eye. In the next shot, the butter is back on the knife. Then in the shot where Jerry sees Tom letting off some steam, the butter has disappeared. Then when Tom tears up the telegram, the silverware, butter and lemon have disappeared. When Jerry is searching for the shred that says "EVEN A MOUSE", the lemon and knife are back again. Then when Tom loses his temper and attacks Jerry, the lemon, knife and the dish that the lemon was on have all disappeared.
Continuity mistake: When Tom tears up the telegram into little pieces and throws them onto the plate, the number of pieces decrease between shots.
Continuity mistake: When Jerry goes to the door, you can see the telegram is by the letter box and after reading the telegram, he throws it away and jumps for joy. But when Jerry goes to show Tom the telegram, it is now back in its original position.