The markings on the dead rabbit are clean - probably too clean to have made with claws, by Rust's estimation. His dissection of the creature shows that it was well-fed and otherwise matches expected Earth rabbit anatomy; it was probably taking care of itself pretty well before something captured and violently murdered it. Rust does not spot any tracks near the pit trap (rabbit or otherwise).

The fish skin seems like it came from a carp of some kind, and definitely doesn't match the large scales of the skin Rust has been sleeping in.

The broken arrow is lying around, once again partially obscured by some undergrowth. The damage to the shaft and what's left of the badly chipped arrowhead is too significant to appropriately compare it to the other arrows Rust has found.

The dog whistle is plastic, and though it doesn't look outwardly broken, it makes a loud rattling noise when shaken and wheezes pathetically when blown on. Some internal bit of plastic has probably snapped and is obstructing the airway.