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

1. Modify the object to ensure it maintains a consistent pentagonal cross-section throughout its height. This will make the object resemble a pentagonal prism.
2. Adjust the lower part of the object to form a rectangle. Currently, it maintains a pentagonal shape which is incorrect.
3. Ensure the object is extruded uniformly in one dimension. The current model changes shape at the top, indicating it is not a simple extrusion of a single shape.