Continuity mistake: When Warren T. Rat leads Fievel to the door of a tailor shop where his family is supposedly located, its hinges vanish right after Fievel jumps into the elevator. (00:27:45)
Continuity mistake: In the opening scene where Tanya and Fievel receive their Hanukkah gifts, Papa can be seen tying on a new headscarf for Tanya in front of a mirror. When Tanya turns around to admire it in the following shot, Papa's hands are still working but his reflection isn't visible in the mirror. (00:03:50)
Continuity mistake: In the opening shot of Mickey O'Hare's wake, the wooden door is visible with hinges attached on its right side. Pretty soon Gussie makes her entrance looking for Honest John, but now the hinges have switched sides. (00:38:00)
Continuity mistake: After Gussie Mausheimer walks out of Mickey O'Hare's wake, Bridget asks to speak with Honest John regarding Fievel's family. Pay attention to the attendees in the background who are gathered around Mickey's picture: they keep disappearing in every other shot throughout the remainder of the scene. (00:40:20)
Continuity mistake: When Fievel is curiously wandering around below the ship's deck he discovers three barrels of herring, each one of which is specifically marked for breakfast, lunch and dinner (dinner being closest to the staircase). A little while later, Fievel is being tossed around on a bar of soap that carries him back to the barrels of herring. But when he lands on the dinner barrel, it's now marked as breakfast instead. (00:10:15 - 00:16:00)
Continuity mistake: During "A Duo," Fievel is standing on a cage tray which Tiger slides next to a dirty floor mirror. Once Tiger begins singing the chorus, the tray disappears - only to reappear in its original location once Fievel wipes the mirror clean in the next shot. (00:57:05)
Continuity mistake: During Mickey O'Hare's wake, Gussie Mausheimer opens the door and starts talking to Honest John about organizing a rally to help get rid of the dangerous cats. But during her last sentence regarding uptown mice, notice how the door has vanished. (00:40:00)
Continuity mistake: When Warren T. Rat is near the museum's entrance trying to negotiate with Gussie, he's wearing his purple nightcap and a rat disguise. But Tony's not convinced he's really a rat, so he sets out to expose Warren T. by firing his slingshot. In the following shot part of Warren T.'s disguise falls off as planned, but he's now holding the nightcap instead of wearing it. After replacing the nightcap he tries to explain his way out of the situation, but once again in the very next shot where Tony takes aim to fire a second time, he's suddenly shown holding the nightcap. (01:00:30)
Continuity mistake: When Warren T. Rat is playing his violin off-key, there's a female statue behind him adorned with candles, and at first glance it seems to be in good condition. But after Fievel witnesses Warren T. shedding his rat disguise, the statue is now significantly cracked in many places. (00:50:40)
Continuity mistake: In the scene where Fievel walks in on a group of cats playing cards, Tiger slaps down his hand and yells "Rummy!" But once he gathers the cards and holds them up again, there's a 3 of Diamonds visible - which wasn't part of the original hand to begin with. (00:50:00)
Factual error: When Gussie Mausheimer is pointing to a map and outlining the secret weapon plan, east and west are switched on the compass rose. (00:52:55)
Continuity mistake: During the storm, two mice are shown playing a game of chess on a board which floats back and forth with the ship's motion. After the first mouse makes his move, it drifts across to player two. However, in the very next shot two things occur: the board's color changes from black & red to black & white, and the square pattern arrangement changes to that of a checkerboard (which means a black square is placed at the lower right hand edge of each player's side). (00:14:35)
Continuity mistake: When Fievel is making his way through the sewer looking for Papa, he enters the Mott Street Maulers' hideout where five cats are seen playing poker. The gray cat with a blue shirt is sitting on the carpet's edge, but in the next shot he's somewhere towards the middle instead. (00:49:25)
Continuity mistake: When you see the water tower where Fievel is sleeping, the moon has already risen in the sky. But when he and Tanya start singing, the moon is just starting to rise.
Continuity mistake: While Honest John is pushing both hands against the secret weapon to keep it from escaping, a clock strikes 6:00 A.M. At this point he raises his left hand and shouts, "Release the secret weapon." But when the shot changes, he's suddenly got both hands in place on the weapon once again. (01:02:00)
Continuity mistake: At the beginning when Papa walks toward Tanya with a present hidden behind his back, notice how her hands pull apart from one another between shots. (00:03:50)
Continuity mistake: When Fievel is running along a clothesline towards the sound of a violin emanating from a nearby apartment building, notice how the rope is attached to the siding at first. But one shot later the rope can be seen attached to the window sill instead. (00:31:50)
Continuity mistake: In the scene where Fievel speaks to Tony for the first time about finding his family, he jumps up from the lower bunk bed and walks towards the window with a plan in mind. But between shots, several things change: Tony is awoken when Fievel accidentally kicks the top bunk (whereas he was fully alert and talking in the previous shot), clothespins holding the bunks together suddenly become wrapped in string around their centers, an orphan mouse appears from nowhere - sleeping by the window, and Fievel instantly switches from lying face down to belly before jumping out of bed. (00:28:50)
Continuity mistake: As Fievel is sleeping in the hay beneath a broken window at Orphan Alley, three bullies approach and start taunting him. In the next shot, Fievel is suddenly wrapped in a blanket, which is quickly pulled out from underneath him by the first bully. (01:08:30)
Continuity mistake: When Fievel is struggling to avoid the other cats on the player piano, Tiger appears on its right side and pounds the keys, just missing him. But Tiger instantly disappears from his location in the very next shot where Fievel jumps up to the music rolls. (00:51:55)
Answer: Warren T. grabbed Tiger and told him he was fired.Tiger did eventually leave some time after that though.