When Col. Hogan draws measured circles on a map, the first is supposed to be 108km, the second 220km, and the third, 250km. The second circle should be more than twice the diameter of the first, yet he never actually changes the size of the compass.
When the gun drops off the roof and discharges, the bullet travels through the office window and hits a vase. A bullet hole is visible when Col. Hogan opens the window to look out, but in the next scene the window pane is intact with no bullet hole.
When Klink and Schultz take cover from the fake air raid, they're just a step in front of the window of the barracks, a good six-to-eight feet away from the corner. When Hogan and his men take the debris off of Klink and Schultz, they are at the corner of the building, several feet away from the window.
LeBeau knocks the gun off the roof. The impact with the ground causes the gun to discharge. The bullet appears to travel through the window in Klink's office and into the vase. The hole is in the middle pane on the right (from inside Klink's office), at about Hogan's neck. The vase is on a desk that is no higher than Hogan's waist (if that). The bullet appears to have traveled from ground level through the window pane to the vase, going up from the ground then down from the window to the vase. It doesn't make sense that the bullet could make such a change in trajectory by going through the window.