>>9400834There's a pretty nasty gap between the cab and noses of the train. There's a bunch of people that've documented how you can fix this while still having it be able to navigate Lego's R40 curves. If you want to fix that along with the derailing thing the other anon mentioned Jang has a video on that too
https://www.youtube.com/watch?v=KSKqlwXFTxUIf you're completely new to Lego trains and have zero track, I'd honestly recommend getting a 3rd party set of curves with a larger radius over using Lego's curves. The wider curves will make for much better turns for the Crocodile and prevent it from derailing as much. If you're European go with TrixBrixx
https://trixbrix.eu/en_US/p/Curved-Track-R56/33If you're American go with BrickTracks
https://www.bricktracks.com/product-page/r56-curve-x8-pfKeep in mind you'll need 16 curve pieces total for a full circle no matter where you buy from.