Continuity mistake: At Mouse Garden headquarters outside of the Commission of Immigration, several vendors are trying to sell things to a crowd. Below a top hat is a sign which distinctly reads 'Mouse Garden'. But fast forward to the one offering a used ticket to Chicago right near the headquarter entrance and you'll see how it now says 'Immigration Mouse Garden' instead. (00:24:35)
Continuity mistake: When Fievel discovers that Warren T. Rat is actually a cat in disguise, the hat tucked into his black belt disappears between shots. (00:51:20)
Continuity mistake: When the secret weapon is released from Professor Digitalus' Museum, it demolishes the door and scares every cat onto the Star of Hong Kong's anchor. Just a few minutes later, Fievel can be seen passed out on an eyehook in the vacant museum. That's where a flame ignites a trail of kerosene, but when it soon becomes a full-blown fire, the door is once again intact (locks, chains and all) as though nothing happened. (01:03:10 - 01:05:55)
Continuity mistake: After Fievel tumbles from the railroad tracks, he can hear what sounds like Papa's violin coming from a building nearby. While he's running towards the street, his hat turns itself around between shots. (00:31:30)
Continuity mistake: After Fievel gets captured by Warren T. Rat, he's ordered to work alongside numerous other mice in a tailor shop. In the following scene where everybody's asleep, Fievel jumps from his bed and walks over to the nearest window - making a reference to Rapunzel's hair and how well it would work to escape with. All of a sudden, two long white sheets conveniently appear on the floor behind him out of nowhere, from which he makes a long rope to rappel down the side of the building (not unlike Rapunzel's hair). (00:28:50)
Continuity mistake: After Tony whistles at Fievel from atop the Hester Street lamppost, Fievel's blue hat can be seen lying in a puddle. But between shots the hat moves itself onto dry ground. (00:33:25)
Continuity mistake: When Warren T. Rat is playing the violin off-key, he hits a bad note and blames his fake nose for getting in the way. With the bow still in hand, Warren grabs his nose and proceeds to twist it off. But the bow vanishes in the next shot as his nose snaps free. (00:50:50)
Continuity mistake: During "A Duo", Tiger picks up Fievel's cage and places it on a nearby step. Between shots, the cage tray decreases in size significantly (judging by the overhang). (00:56:35)
Continuity mistake: During Mickey O'Hare's wake, Honest John's shot glass refills itself between shots, at the point where he asks Gussie Mausheimer, "What's a wawwy?" (00:39:40)
Continuity mistake: When Papa's story is interrupted by the Cossack cats, some of the tableware gets knocked over and broken. But seconds later, in the shot where Fievel runs outdoors with a pot and spoon, all of the broken items reappear intact. (00:05:45 - 00:06:25)
Continuity mistake: When Fievel emerges from beneath a tea kettle cover and collapses onto the snow, Mama walks over and scolds him. A moment later, Fievel's feet are suddenly missing their pads. (00:07:20)
Answer: Warren T. grabbed Tiger and told him he was fired.Tiger did eventually leave some time after that though.