Look more closely at the flag. There’s a bit of a white border on the top. There is also a splotch of red extending from the end of the flag on the top right. The last red stripe on the bottom is cut off. A wide angle lens wouldn’t explain the difference in perspective between the people and the chairs. It also doesn’t account for the different angles of the shadows.
Look at the big honking patch of blue that doesn’;t belong on the left hand side of the flag. There should be hay bails there but it’s blue.