Visible crew/equipment: Before the American soldiers attack the half-track in the field we see Upham walking. Watch at his left shoulder you see a square shadow moving around. It's the shadow of a camera. (01:40:05)
Visible crew/equipment: When Hanks, Damon and company are retreating to the Alamo (across the bridge) the camera pans an overview shot of their retreating and you can see two crew members in the shot - one holding a camera and another supporting member, both wearing white tee shirts on the right part of the screen.
Visible crew/equipment: When Reiben, Ryan, and Miller are in the ditch a side angle shows them all on the same frame, if you look carefully to the right and behind some rubble, a blue tent is visible which is revealed in the special features to be the tent that dailies are viewed.
Answer: These were barrage balloons, commonly used during the war. They are used to stop low level bombing and low level fly bys by enemy fighter planes. The cables attached to the balloons are designed to cut through the wings of the aircraft and to bring them down, so any pilot would have to fly above them, and the balloons would also restrict the view from above.