Some blocks have bugs in terms of gaps in the model or missing/misaligned textures.
I made a collection of screenshots with each a short description of the environment, the block location in the map editor and a reason:
I hope this helps for the graphists to fix these blocks in one of the next updates.
Also want to thank riolu, Tis, JR1988, ThaumicTom and DerStef for helping find some of the bugs.
If anyone else found any other block bugs, be sure to post them below, so Nadeo sees them too!

Greetings,
eFFecT
04/09/18: added a 17th (lagoon) bug
01/08/18: added a 15th (valley) and 16th (lagoon) bug
Edit: added a 14th (valley) bug