Crowning Moment of Awesome: When Robyn's father rescues her from the top of the burning house via helicopter. And accidentally leaves Tom and Jerry behind to burn, though that isn't the awesome part.
Designated Villain: Captain Kiddie's only "crime" was attempting to return Robyn to her legal guardian so he could collect the reward. Sure, he was greedy, but he had no way of knowing Robyn was telling the truth about how terrible Aunt Figg was.
Ear Worm: A couple of the songs definitely stay with you, for better or for worse.
Misblamed: Though the film makes it seem that Tom and Jerry have never talked before the events of the film, in reality many of the early shorts feature Tom and/or Jerry speaking, with Tom speaking much more frequently than Jerry.
Never Live It Down: Tom and Jerry abandoning their rivalry and talking to each other throughout the entire film, only to be upstaged by Robyn Starling and the rest of the human characters. Nearly everyone agreed the film completely missed the point of the series, and most subsequent projects to feature the duo have made sure to avoid this.
Nightmare Fuel: The aforementioned "Dr. Applecheeks closing in on the ice cream cart" moment. Brrr. His character in general counts, actually; portrays himself as a kindly vet who loves animals and allows people to drop off lost pets for him to take care of. But then he shows his true colors, as a greedy con man who makes money off of pets that he kidnaps and sells back to their distraught owners. All the while, he abuses the poor little creatures and treats them less like living things and more like money-making commodities. Even his own henchmen are terrified of him.
Older Than They Think: This isn't the first time that Tom and Jerry are changed from mortal enemies to best friends. The Tom and Jerry Show had the duo as friends and aired 17 years before the movie hit theaters. Problem there though is that's when the shorts were undergoing Seasonal Rot and aren't highly regarded by fans either.
Tom and Jerry also talked and sang occasionally in the original shorts.
The Scrappy: All of the new characters created for this movie; Pugsy, Frankie, Aunt Figg, Lickboot, Captain Kiddie, Squawk, Dr. Applecheeks... and especially Robyn Starling, the girl that Tom and Jerry help to find her lost father, and the one responsible for making Tom and Jerry stay Out of Focus and making the movie being about Tom & Jerry In-Name-Only. The few that aren't universally reviled (Lickboot, Applecheeks to name a few) are only liked because of YouTube Poopremixes and memes.
Pugsy deserves a special mention, as he is the one who got Tom and Jerry to talk and sing about how they are best friends, despite Tom and Jerry being, you know, mortal enemies. Heck, the hatred toward him is so strong, The Nostalgia Critic even shoots the dog's head off in his review of the movie.
So Okay, It's Average: If not for Tom and Jerry being the (alleged) main characters, the movie most likely would have been forgotten within the flood of animated films that tried to copy Disney's success in the early 1990s.
Squick: Aunt Figg and Mr. Lickboot look like they're about to kiss at the end of their Villain Song.
Aunt Figg sucking cream off her fingers after eating an eclair.
They Changed It, Now It Sucks: The general reaction of existing T&J fans to the movie making such drastic changes in tone and content from the original shorts.