Heres a few goofs that Im sure most of you already know. Ill be adding more, but for now, heres 3 of them.
Goof #1

Goof #2

Goof #3

***NOTES***
In Goof #1, the 3rd dead guy is missing from the first shot. Then in the later shot, where you can see Blondie's boots, he appears face down next to the dresser.
In Goof #2, you can see the driver for only a little bit, but you can clearly see the ropes that are used to stear the horses, running into the wagon where the man is sitting.
In Goof #3, the car drives by for about 2-3 seconds.
I will be posting more Goofs, for example, when Tuco is standing on the cross above the grave, with a rope around his neck. In that scene, you can see a car on his right, and possible one on his left. Im not sure if the one on the left is a car, or someone walking.