For photos taken for the 2nd time in the photo booth, El Chivo is wearing the brother's black sportcoat, yet when he subsequently pastes the photo in the album, the sportcoat appears distinctly burgundy in color.
Prior to the crash, the car they are driving is a 1983 or 1984 Mercury Grand Marquis, which was sold in México under the Ford brand name. The car that actually crashes is a 1981 Ford Crown Victoria.
The first time we see Valeria's 'Enchant' banner, her head is covering the 'C', but the next time that the banner is shown, her head is not covering the 'C' at all, then, the last time that we see the banner, the 'C' is completely covered by her head again.
When "Chivo" gags the first brother, the gag completely covers his face from the nose down. In the next morning the gag is neatly folded around the mouth.
When the industrial is murdered by El Chivo in the restaurant, peasants are seen walking in the street. One of them is a woman with sunglasses. That same woman appears at El Chivo's ex-wife's funeral.
During the car crash, stabilizing bars, to further strengthen the roof and protect the stunt driver, are visible in the black car. These bars are on both the driver's and passenger's side and run diagonally from the roof to presumably the floor, as in a race car. The bars are not visible prior to the accident or after the accident. This particular vehicle was almost certainly just used for that one scene/shot.