- During the film's climax, when the Rat sneaks into the house to attack Jim Jr., where were Si and Am? They ARE FREAKING CATS! And cats are mortal enemies with rats! Why when they were absolutely necessary and could do something good they aren't there?
- Maybe Aunt Sarah had put them to sleep by that hour or they were just on other room.
- At the film's climax, after Tramp kills the Rat and Aunt Sarah comes to the scene, locking up Tramp in a closet as she initially thinks that he had woken up Jim Jr., why Aunt Sarah didn't smell the Rat's foul odor upon entering into the room? Maybe she could have still suspected about Tramp at first, but at least she could have smelled something suspicious on the room, find the Rat's corpse and put two and two together...
- It's likely that Aunt Sarah didn't think about this as her grand-nephew had been apparently disturbed by Lady and Tramp and just assumed that Lady and Tramp had tried to attack him, possibly in revenge of her treatment on Lady. That said, immediately after she locked up Tramp into the closet and put Jim Jr. back on his crib, she took Lady out of the room and locked up her on the basement. Due being upset, she possibly didn't have time to smell the rat's scent and consider other possibilities.
- Aside of that, who says that the Rat smelled bad on the first place? Though it's common for rats to smell badly due most of them living on sewers, if a rat lives on a clean environment, such rat can be able to not smell at all. Maybe the Rat didn't live on the sewers and was actually clean.
- Or maybe Aunt Sarah suffered anosmia? If she had lost her sense of smell, then that may have been the reason she didn't smell the Rat in case the Rat's corpse did smell.
- This entire question rests on the presumption that the rat had any kind of "foul odour" to begin with. Contrary to popular belief, rats - even wild ones - are naturally very clean animals. The only reason one would carry a "foul odour" naturally is due to its environment (say, living in a sewer) where the smell would be a by-product, not something necessarily caused by the animal itself; there's no indication that the rat, though looking extremely feral, would have been living in that kind of environment, more likely it had a permanent home somewhere in or close to the garden of the house. Also, corpses - even rat corpses - don't begin to stink the second they drop dead. Aunt Sarah entered the room at most five minutes in-universe after the rat was killed and most likely she didn't even take that long; that's hardly enough time for any kind of smell to develop from the rat's corpse. There's honestly no earthly reason why she, being established already as hating dogs and especially not wanting dogs around the baby, would have had any reason not to think this clearly stray dog had somehow got into the house and tried to attack the child.
- We're told that dogs can't talk to non-human primates due to the latter being "too closely related to humans". Fair enough, but if Animal Talk in this world comes down to phylogenetic relationships then how come Lady and Tramp have no trouble conversing with an alligator? They honestly should've had an easier time communicating with the apes since they, like dogs, are at least mammals.
Headscratchers / Lady and the Tramp