I thought maybe that was on of the springs from a Panzer III seen up at the rest of the hill, but after reviewing the back plate and seeing one of the side engine vents flipped and buried behind the turret ring, I concur
After digging through Germany's Panther Tank, Tigers I and II And Their Variants(The crappy translated version of Tiger Und Seine Abarten), and Panzer Tracts 5-4, the depression is listed as -8/+15 for the KwK 43, which matches the planned specs for the Schmalturm 88. Cross referencing this with the project to install a rangefinder in the Tiger II, they might be sharing the same rangefinder design. If this is true, the plan for the Tiger II's turret was to raise the turret roof ever so slightly(max height increase of rearward edge: 25mm) to permit the full range of motion with the rangefinder, maybe that could have been under consideration. Though on the other hand, they had already achieved these gun depression angles with the Schmalturm as-is for the 75mm L/70. I suppose I'd have to sit down and compare the dimensions of the two guns breech setups
Oh derp. Just noticed Doyle made an interior drawing of the Schmalturm 88 for GPT. *headdesk*
As for the muzzle brake, that was one of the planned specs. The Germans decided to live without it.