Based on the answers provided, the following corrections need to be made to the 3D object:

1. The object should be redesigned to resemble a right triangle. This means it should have a flat, two-dimensional shape with one 90-degree angle and two other angles that add up to 90 degrees.
2. The object should only have three sides, which is characteristic of a right triangle. Remove the additional sides to achieve this.
3. Ensure that one of the angles in the triangle is 90 degrees. This is a defining characteristic of a right triangle and should be clearly visible in the design.