In level for picture taken in 1962 (the one with the guy with the spear): isn't the sound the dinosaur makes the same as imps make in original Doom games?
You could have statistics after each round, for example how long it took to shoot a target on average, how many percent of kills were headshots, shooting accuracy etc.
People don't mention acid cannon is op, but it is. When you upgrade the secondary damage and get 3+ of these you can keep up a pretty much constant barrage destroying everything.
:D