Hint: Text for Axe Easter Eggs
On the Fremont Street level there is a bottle of Axe on a ledge. Shoot the bottle and the roof on Fremont Street changes to an animation of a girl in a bikini with some Axe materials in neon. A movie opens up showing some outtakes and pretty funny Rainbow situations/early animations.
Hint - Unlocking Weapons (Campaign)
After destroying the opposition in single player campaign, don't forget to pick-up each new weapon you come across. While you don't have to keep a weapon and finish a map to unlock it in your customization menu, you do need to hold onto it briefly or your profile will not save it.
Another advantage is once you "claim" the weapon, you can die or restart the mission entirely and use it in the stage you got it from. This way, all the enemies you drop pretty much restock that weapon's ammo and you literally will be carrying a portable ammo dump throughout that stage.
Note: you need to reload your profile's last checkpoint each time you boot the game to get your gear back. If you choose to load a stage without loading your last checkpoint, your previously earned weapons will be lost.
Private 2nd Class: All Starting Equipment
Private 1st Class(3,000 pts): Headgears 1: Tactical Helmet, Balaclava
Specialist(8,400 pts): Rainbow Weapons: MP7A1, SIG552, USP40
Corporal(14,500 pts): Camo 1: Desert, Urban, Russian, Guerrilla, Fall, Desert 2
Sergeant(23,500 pts): Tactical Armor: Raven Recon Armor, Vulture Combat Armor, Falcon Assault Armor
Staff Sergeant(38,500 pts): Headgears 2: 3 Hole Balaclava, Baseball Cap, Breathing Mask
Sergeant First Class(56,500 pts): Camo 2: Flecktarn, Orange, Swedish, War2k5, Alpen, White
Master Sergeant(82,500 pts): Freedom Fighter weapons: AK47, Raging Bull, SV98
First Sergeant(109,500 pts): Headgears 3: Bonnie Hat, Beret, Tinted Goggles
Sergeant Major(139,000 pts): Black Market Armor: Typhoon Recon Armor, Cyclone Combat Armor, Hurricane Assault Armor
2nd Lieutenant(172,000 pts): Camo 3: Pink, Blue, Woodland, Wasp, Sand, Crimson
1st Lieutenant(214,000 pts): Headgears 4: Half-Face Mask, Reinforced Helm, Tactical Goggles
Captain(264,000 pts): Mercenary Weapons: MG36, SPAS12, Desert Eagle
Major(333,000 pts): Military Armor: Vier Recon Armor, Diamondback Combat Armor, Anaconda Assault Armor
Lt. Colonel(415,000 pts): Camo 4: Yellow Urban, Red Urban, Tiger, Rust, Urban 2, Grey
Colonel(535,000 pts): Headgears 5: Ballistic Face Mask, Riot Helm, NVG's
Elite(675,000 pts.): Camo 5: Custom 1, Custom 2, Custom 3
On Fremont Street (single-player) locate the Kapone casino entrance. While facing the entrance, look to the player's left and there will be a black AXE Men's Body Spray bottle sitting on a planter. Shooting it once will let you see test footage for R6 Vegas.