Train Rush is Act 4 of the second Chapter: Battle of the Birds. In this act Hat Kid boards the Owl Express once again, but this time it's rigged with a time bomb! Hat Kid must get from the caboose to the front of the locomotive before it detonates.
After Hat Kid spawns, she will have to go inside the train, use your hook at the detonator to detonate the bomb, after that, The Conductor appears on a TV, and warns Hat Kid that the train will explode! Hat Kid must get to the Conductor as fast as possible! While she is running as fast as she can, you can find helpful watches that can give you more time. When she reaches the conductor, he will congratulate Hat Kid and give her a Time Piece, you also gain some Points from completing the level.
After each mission Hat Kid will write about it in her diary, which can be found in her room under the swimming pool of pillows. The diary will only read the entry for the last act that was completed.
"Every time I’m around the Conductor, I can hear him mumbling about his movie. I think he’s trying to figure out some big, huge, impressive, exciting, AMAZING thing to do with his train.
"I mean, OK, *maybe* his movie could use more action or something. Like, um… uh… I actually have no idea what he could do. Being a movie director must be hard."
- In the beta release, Train Rush was first Act for Trainwreck of Science; an early name for Battle of the Birds.
- In the beta release, The Receptionist starts the train's self destruct sequence.
- In the Caboose, a small TV can be seen with a parody of the intro to Kirby's Adventure, a game for the Nintendo Entertainment System.
- In the beta release, the train was filled with purple spheres with faces. These faces can still be found on the buttons in the Lava Car, and the spheres themselves are still present in the loading art. According to Jonas Kærlev, the game's director, these were removed because play testers thought they were enemies.
- The car filled with acid holds three Express Owls that can be attacked and killed. No other Express Owls in this act behave like this.
- In the Beta, the Express Owls were all Science Owls. Unlike the final, these Owls were aggressive towards Hat Kid, and would attack her.
- Even though Hat Kid can enter this act as soon as Murder on the Owl Express is completed, she will be unable to complete it unless she has the Hookshot badge from the Subcon well; As the door to start the main part of the act needs to be grappled onto and is required in the fifth (where the train starts to fall apart) and sixth (the outside area where part of the train flies off) sections of the level.
- If Hat Kid tries to enter this level without the Hookshot badge, the game will display the following message: You're missing a key item and won't be able to complete this act. Enter anyway? Yes! No!