This is most likely a material with some volume effect to it, that is applied to non-closed geometry (think glass or water, applied to a flat plane). Because the geometry is not closed, and cameras can now detect when they should be classed as being inside a volume (to allow the "camera half submerged in a pool" type render), then the camera sees itself as being inside a volume.
Solutions: Close the volume (don't use flat planes, since nothing in reality has zero thickness). Remove the volume effect from the material. Or use Corona 13, that has a fix for this (basically looking in two directions rather than one to establish whether the camera is inside a volume).
