Visible crew/equipment: When Maguire raises his hands together to say the prayer, you can see the black wire of a microphone, running up into his shirt. (00:06:50)
Visible crew/equipment: When we see first Kate open a door, it opens, and she leaves her hand up, then slowly lowers it. Look to the left of the cube-shaped doorway, and you can see in the room behind her, the edge of a stand or table or some equipment, which obviously shouldn't be seen there. (00:07:25)
Visible crew/equipment: When we first see Kate, she opens a door, and then, she climbs through. As she climbs through, you can see down her blouse, and you can see a microphone. (00:07:30)
Visible crew/equipment: When we first see Mrs. Paley coming through a door, reflected on the shiny surface of the door is a boom mic. (00:16:35)
Visible crew/equipment: At one point when everyone is escaping through the doors away from the moving wall, when Simon is the last one to climb through the door. When the door closes we can see a persons arm reflected in the door. That is an impossible position for any of the others to stand in, so it has to be a crew members arm. (00:22:15)
Visible crew/equipment: When Mrs. Paley opens one of the portals, she sees herself getting killed by Simon, then Simon getting his head taken off by something. Then the portal door closes, and a camera and crewman are reflected in the portals shiny surface. (00:42:30)
Visible crew/equipment: When Simon shouts to Kate "You're a dead woman!" because she goes back to rescue Sasha from the Razorsphere, the door shuts in his face, and you can clearly see the camera crew reflected in its shiny surface. (00:54:00)
Visible crew/equipment: When Julia and Max are talking about Alex Trusk, Max then goes on to tell Julia that he designed the concept for the variable time-speed rooms. As he walks across the room, exclaiming "It was for a game! Now here we are!", watch the floor to the right of the screen, and you can see some black crew equipment laying there, which is nothing that belongs to Julia or Max. (01:08:25)
Visible crew/equipment: When Sasha says "I wish I had your spirit" to Kate when Kate is climbing up to open a door, you can see the reflection of the boom mike moving as Kate is climbing. (01:19:05)
Visible crew/equipment: After solving the "60659" mystery, Kate opens a portal, revealing nothing but darkness outside it. It then cuts to a shot of the watch ticking, then back to Kate who is still kneeling down. In this shot you can clearly see down her blouse, and the long black mic wire and mic is very visible. (01:22:45)
Visible crew/equipment: As all the different realities start collapsing into one space, Kate goes to open one of the doors. As she climbs up to open it a boom mic is reflected in the door's shiny surface.
Visible crew/equipment: Just after Mrs. Paley joins the others, the door closes and a boom mic can be seen in the reflection of the door, lowering down a bit.
Chosen answer: I'm inclined to think it was longer than a month because of the lack of proper needed care for such an injury would prolong the healing process. But he only had a handful of souvenirs on him, which means he probably stopped collecting after a while. I concur with your cannibalism theory, there's no other way he would have survived. However that doesn't explain what he could have done for water. This theory of Simon spending possibly months in the cube also brings up the question: If the cube breaks down at 6:06:59, then how is it possible to live in there for months? Well, as we saw, certain rooms have slower and faster rates of time. So, he could have spent all that time in a room with a slow time rate waiting for people to wander into it and feed off of them.