There is no blood on the deck where Alan is shot, but a large pool of blood is found under the deck. Alan was not shot and the blood under the deck leaked between the floorboards.
When Sarette runs to her car, there is a star in the lower left windshield of her car. As she begins to back out, the star is in the upper left corner. When she pulls forward the star is once again in the prospect corner.
When the cleaning lady went to the patio below the deck to try to get the heel unstuck from between deck planks, she did not notice the very large red puddle on the patio. Also, when she walked over to get the chair and position it under the heel, she would have had to walk through the still-wet puddle, yet none of the blood was on her shoes when she climbed onto the chair.
When Sarette is on the deck and her shoe heel gets stuck, her foot is parallel to and in line with the deck boards. In the close-ups, her foot and shoe are at right angle to the boards.
Sarette calls Allen person-to-person from New York, but when Allen answers the phone, he didn't identify himself. On a person-to-person call, the operator would have asked his identity.
Allen was killed before 10 p.m., and his body was removed shortly afterwards. The pool of blood should have been dried by the time the cleaning lady discovered it the next morning (likely at least eight hours later), but it was still wet to the touch when she put her hand on it.
When Sarette finds the body on the balcony, the top of the interior soundstage is visible inside the sliding door behind her.