You can obtain this through the 'Play' mode. (Credit to loserb0i)
38 Shortcuts to take
1. Just after the factory take an immediate right (most AI cars go this route by default it seems).
2. Get the key by following the path which starts immediately to the left of the rapids, and use the key to the right of the factory entrance.
1A. At the start of the race there is a dirt road off to the left by the first corner, if you time it right you'll get the shield key.
2. After you drop back down from getting the key, there is a shortcut immediately to the left, keep you're eye out as it is quite easy to miss.
1B. Take the furthest right path through the castle for the locked shortcut.
3. There is a big jump that you can land on a high route up through the top of a castle, you need a full KERs corner boost to make it.
4. Just before the final couple of corners there is a small narrow road to the right which cuts them both (behind a little blue hut).
1. Right at the beginning go to the left to skip the first chicane.
2A. Collect the key, as you enter the Colosseum take the path on the right.
3. After collecting the key to the locked shortcut, the road splits, to the right is a group of charging shields, to the left is a little ramp, take the ramp.
2B. After the long straight where you weave between the broken bits of the bridge, they'll be a left hand corner, stay on the right and keep your eyes open for a gate.
1. At the first corner you want to cut across the grass and hit the boost pads.
2. After the next KERs corner take a sharp right, jump up on the roof to the right and get the key. in the big round area of the carnival there is what looks like a chicken head towards the back left, that's the gate to go through.
3. On the big wooden part of the track there is a narrower path off to the left that goes across the pond.
4. 2nd lap just before the carnival take the ramp on the left to jump onto the roof and stay on it all the way to the end.
1. Just after the roller coaster there is a chicane, head towards the right and go over the gravel trap to skip it.
2. Collect the key from just inside the first building, there is a path immediately to the left as you enter, use the key a little bit later before exiting the building on the left.
3. On the next lap just after you come off of the moving platforms held up by cranes, you'll have to go around hairpins in the sand, after the first there is a path in the wall on the right.
4. Immediately after the last shortcut there is a KERs corner, charge your boost and go straight forward, aim for the ramp, and jump over the puddle.
1. Just after the fountain area take a sharp left (just before there is two moving vehicles), you'll go through a shopping mall kind of area, this is where you collect the key, as you come back onto the road take a right through the gate (just before the next hairpin).
2. Immediately after the locked shortcut take a right up onto the path (you'll go over a swimming pool).
3. On lap 2 after the tunnel there is a chicane, cut across the grass on the right to skip it.
1. In the fountain area take a right for an alternative route, this will get you the key. just after the start/finish line there is a split section where the track is divided by a wall as you go down stairs, take the left path and go through the gate.
1. Just after the stadium at the beginning take a right out onto the docks and ride across the piers.
2. On the straight with trams take a left path to find the hidden key, use it as you enter the sharks mouth on the right hand side.
3. On the next lap back on the straight with the trams there is a jump over a sculpture on the right.
1. As you get to the dirt track area, head to the left where there is a ramp.
2. When you see the first set of tractors, head right through a barn.
3A. Get the key from the jump to the right of the first pit lane.
4. After the dam cut the first 90 degree corner.
3B. Take the locked shortcut, its a gate just to the left of the last shortcut.
5. Head straight through truckasaurus' legs and ride over the slow dirt behind him.
6. 2nd lap, during the canyon area before the dam, ride the higher path on the left all the way to the dam.
7 & 8. Towards the end of the lap (just before truckasaurus, you slalom around a couple of field goals, cut across two pieces of grass here for two shortcuts.
9. 3rd lap, in the canyon area, they'll be an opening to cross a small stream, cross it.
1. Near the start, the road forks, to the left tarmac, to the right it drops down onto dirt and has 3 red boost pads, take the dirt road.
2A. Collect the key from inside the first factory, there is a path immediately to the left upon entering.
3. After jumping out of the factory you slalom around 3 hay bales, planes fly by and blast the hay bales away, you want to time it so the planes have blasted the hay away before you get there, and cut across all 3 corners
2B. Take the shortcut, as you enter the first airfield, at the back right of the field is a big plane you cut through.
1. In the area with the robot girls on wheels go out of the building to the right, follow the path to get the key. use the key just after the start/finish line through a big red semi circle fan.
2. On the 2nd lap, right after the building with the Japanese robot geishas just outside of that is a grass shortcut to take.