Playing the original Quake levels (without using modifications of any kind), I noticed there to be texturing problems on the surfaces of some areas. This only happens when the camera is moving (either vertically or horizontally), as the glitches are static should the camera remain still. While moving the camera, the glitched part begins to flicker until player movement is stopped completely. Interestingly, this effect is not seen on models. Would appreciate if it be patched in later updates.