I found the tail light housing extreeeeeeeemely difficult to pull-out (2006 LR3 HSE). And, yes, it pops out straight backwards. The housing is held by two spearheaded type clips that will eventually release when enough force is applied. These two clips are located towards the top and bottom of the housing (i.e. on the opposite side of where the two screws are located).
I couldn't pull it out by hand. There is just no good place to grip the assembly while pulling straight backwards. So, I ended up prying it out using a thin piece of scrap plywood about 1/8" thick (4" x 4"). The plywood provided a much larger surface area compared with using a large flat bladed screwdriver which might break the plastic housing or dent the sheet metal.