In the Minecraft: PE multiplayer protocol there are a few packets that don't use the standard data types. Most of them don't cause bugs now, but a few of them could do in the future.

UseItemPacket

The Item Damage (6th field) should be a short instead of a byte.

LevelEventPacket

The X, Y, Z fields are shorts, instead of integers.

EntityDataPacket

First, this packet only is sent for Tiles... so the Entity part is confusing
Second, the X and Z fields are shorts instead of integers.

ContainerOpenPacket

The Slot Count field is a byte, while in ContainerSetContentPacket and ContainerSetSlotPacket the Slot Count/Index is a short.

ChatPacket and MessagePacket

MessagePacket is used for player chat and ChatPacket for server messages (like when you can't sleep on bed). A bit confusing