While out exploring, Zack, Rex and Axle come across a low bridge. Axle can drive under fine but Zack gets stuck. They call the Construction Zerbies to help make the bridge tall enough not just for Zack, but for Rex as well. After this is done its fine for Zack, but Rex still can't make it. They realize they also need to make space under the bridge wide enough for Rex as well.
Zack and Rex are exploring when they come across a small stream. They decide to try to cross the stream, and they think back to a floating log bridge they took to get across the lake. They make a floating log bridge but when Zack gets on the bridge the current of the water pushes the bridge down the stream. They try, try again, this time to make a bridge that won't move. A bridge of dirt! But when Rex pours in a load of dirt - it just gets washed away. Rex and Zack know there's a way to solve the problem, but they have to but their hoods together to figure it out. Rex realizes that if they make a log bridge that is above the water, then it won't get washed away and they can cross. No sooner have they made the bridge than Rex is in the water with his life-jacket, trying it out from below as well.
While out for a drive, Zack, Lily, Rose and Goldie all hit the same rock and they all get flat tires. Rex brings his trailer out to carry them back to Mika's Shop so they can get fixed, but the trailer isn't big enough to fit 4 broken Zerbies. With a rainstorm coming in they have to figure out a way they can all get back to Zerby Town. They try getting on the trailer facing forwards, but that only fits 2 Zerbies. They try sideways, which works a little better, but still only fits 3 of the 4. They try piling on but they just end up falling off when Rex starts to move. Even using sticks to make the trailer bigger doesn't work. Finally, Zack gets the idea that if everyone give him their broken tires and he gives the others his working ones, then he can ride the trailer with 4 broken tires and the others can drive home.