You can get studs quickly by walking or driving through the hub areas and breaking things to get as many studs as possible. When you go to a different area and return, everything will be back in place so you can repeat the process. This is especially effective if you have stud multipliers active.
If you activate all of the five stud multipliers at the same time, each stud you collect will be multiplied by 3840.
To earn the "To the Invisible Jet!" achievement (Xbox One)/trophy (PS4), you must find and destroy Wonder Woman's invisible jet.
Go to the Cloud Cuckoo Land hub area in Free Play mode. Use Unikitty or another kitty to destroy the rainbow cloud bricks to your right. Use the rainbow bricks to build a launch pad, which will help you reach another cloud. Aim an attack, such as a boomerang through, at the air to your right. The jet will explode.