When you see Shawn's cell phone in the trunk, it only shows the first text message to Gus.
Henry sees the peace sign followed by the yellow reflector, then the orange cone and finally come upon the remains of the tail light that Shawn kicked out before he could then see the other stuff, so he and Lassiter are apparently driving the highway in the opposite direction that Shawn's kidnapper drove, so they are starting their search at the wrong end of Shawn's clues.
Henry says that the yellow reflector is the last clue that Shawn left in the text message. It was the first (the peace sign was last).
When Shawn is being held at gun point he squints as the flashlight is pointed in his face but the shot before and after shows the flashlight being pointed down.
When Rollins holds a gun to Shawn at about 20 minutes, it goes from his chin to his shoulder and back to his chin in different shots.
While how the ice cream truck ended up on its side isn't shown, just bumping it with a pickup truck wouldn't do it, and it definitely wouldn't work on an armored truck which is much, much heavier.
The slide on the pistol doesn't move when Shawn shoots at the bad guy's truck.