Revealing mistake: When the stretcher is being lowered down on the line, the high tension steel wires can be seen under the hessian rope.
Suggested correction: I don't see this as an error, because just before they lower him down, it is obvious that they have rigged a tripod and cable at a much lesser angle than straight down the face of the cliff. Once the cleanup phase started, additions like this would have been normal to remove the dead and wounded.
I am 100% certain this is an error.
The stretcher is seen lowered down hung from ropes tied at each corner, which would have really happened. Obviously this wouldn't meet safety requirements for filming, so they've "hidden" steel cables in the rope. The error is that the cables and the screw-in anchors in the stretcher are visible. Also the rope on some of the corners is visibly slack as a result.
This doesn't refer to the tripod and cable rig. Just as the stretcher starts moving, the camera shows it moving off to the left with the other soldiers watching on. One of the soldiers is holding one of the ropes that attach to the stretcher. When he lets go, it reveals that the rope is frayed, revealing the steel wire that is threaded through the rope. It's the wire that's attached to the stretcher, not the rope.
Revealing mistake: When Desmond Doss slides down into the tunnel to hide from the Japanese there are rats crawling over the body of a "dead" Japanese soldier but his breathing is visible at his stomach/belt. (02:15:00)