A group of kangaroos is called a mob

A group of kangaroos is called a troop, mob, or herd.

There is a misconception that a small group of kangaroos is called a court. “Court” has no reference at all to a group or collection of kangaroos. A “kangaroo court” is quite different, and refers to sham legal proceedings where the outcome is decided more or less in advance, regardless of witnesses and the appearance of genuine proceedings.