One of the questionable design choices was the integration of 802.11a. Implementing 802.11a, which is rarely used by anyone, meant that a dedicated power amp, antenna, and possibly the cause of another Wi-Fi-dedicated PMIC needed to be included.
Another thing to note is its antennas. Instead of the traditional metal prongs used in most phones, RIM has used what appear to be stickers. These pretty much surround the back of the device.
These placements of the antennas are educated guesses, however. What seem to be obvious placements of the antennas are due to the use cases (holding the phone to your head, or cradling the phone while browsing will cover up areas of the device).