Here is an in-depth guide through all of the courses and their shortcuts. Once you get a gold trophy on every cup in every CC you'll unlock a Extra Mode and a new entrance screen. Extra Mode is like a 200cc and you navigate the courses, only they are reversed - a left turn would now be a right.
Mushroom Cup
Luigi Raceway
This course is very standard. It is almost like an oval. The only things you have to watch out for are the two turns. But that isn't a problem really. There are no shortcuts.
Moo Moo Farm
Moo Moo Farm is rather annoying. It has a basic oval shape. The only hard parts about this course are the gophers that pop out of the ground periodically. Also, watch out for the pillars right before the end.
Koopa Troopa Beach
I just love this course! It has two shortcuts. Tis course is very easy except for the palm trees near the end and getting into one of the shortcuts. The first shortcut comes when you come to the stone arch. GO to the right and across the bridge of sand for a shortcut. The next one requires a mushroom. After the stone arch, keep going until you see a ramp leading into a small tunnel. Use your mushroom on the ramp and go into the tunnel. You will come out at the palm tree. Watch out for the water! If it gets to deep, you will sink.
Kalimari Desert
This course takes place in a desert. The only dangerous parts on this course are the railroad crossings. It is good to have a mushroom to get across if there is a train close by. If you aren't focused on winning, its always fun to chase the train inside the railroad track.
Flower Cup
Toad's Turnpike
Toad's Turnpike can be really frustrating if you aren't good with your kart handling. In this course, you must race and weave through traffic in a challangingrace course. This course can be murder in Reverse Mode because you are racing with on-coming traffic.
Frappe Snowland
This course can be very annoying. You start off in an ice paradise course. The main challenge is the snowmen. They look cool, but if you hit them you will fly up into the air because they explode on impact. Also, you come into a ice canyon right before the finish. Beware because you soon come onto a bridge which may cause you to fall off.
Choco Mountain
This course is very diffulcult. Make sure not to hit the walls too hard or you will wipe out. Also, at one part there are straightaways with now railings. If you fall off, you either go into a chasm or backwards on further back part of the course.
Mario Raceway
Mario Raceway is a great course. It is pretty hard though. There are many challenging turns that if are not handled well, result in off-road slowness.
Star Cup
Wario Stadium
Wario Stadium is very long. There are many challenging sharp turns and jumps. It can be very aggravating too. You can see yourself up on the big screen though and you are in a real stadium.
Sherbet Land
Sherbet Land is a lot like Frappe Snowland. It is very icy so your tires slid a little. Make sure not to hit the penguins or you'll wipe out. Also, there is a problem with the turns. Make sure not to make too many sharp turns or you may fall in the icy water and freeze. Also, the tunnel is a lot of fun except for the penguins.
Royal Raceway
This course can be a real pain in the neck. There are a few hard to make turns but the real thing that mkaes this course memorable is the jump. Its a good idea to plant a banana right before you go off of the huge ramp to stop close racers in their tracks. Also, right after the turn, you can go to your right and see Peaches Castle and where you will recieve your rewards.
Bowser's Castle
Bowser's Castle is pretty diffulcult at some parts. The beggining puts you up against some crashing boulders. Then there are narrow bridges and steep turns with lava as a consequence if you mess up. My suggestion, go full speed through the course and use your top driving skills to come out a winner.
Special Cup
D.K. Jungle Parkway
I always loved this course because of the fast-paced turns and the huge jump. On this course, make sure to stay on the main track and if you choose to take a shortcut across the grass to another road, only stay on the grass for a little bit or you will wipe out from coconuts being thrown at you. Another suggestion, at the large jump, steer hard to your left on the ramp so you land further down the road.
Yoshi Valley
This course is very challenging. You have to go through a multi-path valley and only some paths are destined to lead you to the head of the pack. Here is the path I always take to win. As you enter the valley, go to your right. Keep going and then make a left at the next fork. Then make another left and keep following the path. Then repeat the process or you can experiment with other paths.
Banshee Boardwalk
This board can be a real pain-in-the-neck if you aren't careful. Stick to the middle of the track and whatever you do, don't try any hot moves where you make sharp or round turns or you'll be facing a pool of water and a soaking 8th place. Make sure to following the arrow signs in the house or you'll fall into the water.
Rainbow Road
Rainbow Road is the longest course in the game. It is fairly easy because there are railings everywhere so it is hard to fall off of the track. Make sure that you avoid Chomp because he is everywhere on the track and tries to hit you.