Created a new map and there are 8 wide sections spanning different lengths of the map that are messed up. The biomes change and your player glitches when falling into it from flying.

Loaded the map from version 13w02a.

Before reading the rest, on reload my game was corrected, as seen in another screenshot.

Seed being, -1010813662215941621 (As seen in pictures)

Got map error on loading where different 8 wide sections were glitched.
If I attempted to fly over, then drop in, my character would vibrate up and down and would not let me fall. However walking through it from a regular zone I would pass through unharmed. Unless I were to jump, my character would get stuck for a short second.