Visible crew/equipment: When Chuck is crawling on the floor of the plane to reach the watch, the compartment behind him where the raft was stored, you can see the stairs leading down into the set.
Factual error: Since the can that breaks through the net is an AMJ on the right side of the plane, they must be in either a DC-10 or a MD-11, as those are the only 2 planes that are wide enough to fit AMJs on the right side. However, when Hanks is in the ocean looking back at the plane, it shows the tail as it is sinking into the water. It shows enough of the tail (which has suddenly lost all its paint, in particular the FedEx logo) to determine that there is no intake on it, which signifies that they were on an AirBus. (00:28:00)
Factual error: As the plane hits the water, Hanks is pushed back into the cargo area. He travels through an empty passageway between rows of containers. Though this load configuration is possible, it is not used because it makes no sense. Furthermore, he finally stops against a container that reads AEE7480FX. This creates a couple more problems, as AEEs are not only no longer in use, but they were belly containers, with an angled side on the bottom that fits the contour of the bottom of the aircraft. There could not have been one of these on the topside of the aircraft. (00:26:05)
Continuity mistake: It already shows us that the wings of the plane are submerged in the sea. When Hanks surfaces, he turns around to see an engine (attached to a wing) bearing down on him. Physically this would be impossible even if it didn't show the wings, as the aft part of the plane would have been too heavy to hold that much of itself above the water. (00:27:30)
Continuity mistake: When Chuck is looking through the wallet of the dead pilot, you can see the corner of a dollar bill, then the shot breaks away, when he takes the photo out, the dollar's disappeared. (00:46:30)
Factual error: On Tom Hanks' doomed flight, there is no smoke curtain or solid bulkhead in place. This is a heavy, opaque curtain or solid wall that separates the the topside cargo area from the seating area, designed to keep smoke from a fire away from the crew. On DC10/MD11 aircraft, this is generally a solid bulkhead, and on Airbuses a curtain. This plane should have been grounded until one was installed.
Factual error: When the FedEx packages wash up on the beach, all the contents are completely dry. Even the birthday card from the grandma is completely legible. FedEx does have waterproof packaging, I am sure, but those appear to be just regular boxes.
Continuity mistake: When the plane crashes and Hanks swims to the surface, in the shot from under him, he is barefoot, but when he reaches the shore, he takes off his socks.
Revealing mistake: When Chuck is lying on the raft, and sees the giant cargo ship that rescues him, there is a closer shot of him and the raft as he stretches his hand out in order to be noticed by the ship's crew. He's supposed to be out in the middle of the deep ocean, but the water below him is pale green and very shallow. You can even see the bottom (hard to notice but it is there). It's obviously the water tank they were filming that scene in.
Continuity mistake: After Chuck Nolan (Tom Hanks) injures his hand and throws the volleyball "Wilson", in the following scenes pay close attention to the box that the volleyball is in. One scene the box has a visible tear along the top rim of the box; then, before Tom Hanks opens the box to remove "Wilson" another box appears not torn.
Factual error: Chuck's plane supposedly went down in 1995. During the early parts of the film, you see several Fed Ex aircraft with only two engines (one on each wing) which are Airbuses. Fed Ex had only a handful of these class of aircraft around 1995 making it impossible to see so many of them on the ground in Memphis, or in the Soviet Union for that fact at that time.
Continuity mistake: On the island, immediately after the title indicating "4 Years Later" Tom spears a fish. The spear hits the fish hard and swiftly, and as the camera pulls away the spear is very close to vertical. For the spear to hit that hard and vertical it had to be thrown close to the fish and almost straight down. But as the camera continues to pull further away, you see Tom standing too far away to have thrown the spear in that way.
Continuity mistake: During the scene where he is first at the cave, look in the sky. First, there aren't any clouds then there are in the next scene. If you keep watching, the clouds vary from the different camera angles.
Visible crew/equipment: When he collects coconuts for the first time if you look in the lower right corner you can see some sort of light flashing, I'm guessing maybe a light meter or possibly a two-way radio that the crew was using.