On the 16th of November 2015, between about 2:30 AM EST and 7:30 AM EST, Phantom Forces Beta broke, causing the guns not to work, however, the knife and grenade still worked, thus created a knife/grenade war. The cause of this glitch is not known, but has been fixed since.
This has also happened to Lito's Call of Robloxia 5, in the spring of 2014. At that time, upon arming yoruself with a weapon and trying to shoot/move, you would fly around the map. You could also purchase weapons through killstreaks, such as the knife. Lito stated he may shut Call of Robloxia down permanently, and people freaked out. However, hours later, Call of Robloxia 5 was fixed with the new title "IT'S FIXED :OOOOOOOOOOOOOOOOOOO" Later, Lito began the Roblox Summer Update, which included newer maps, smoother guns, an in-game currency, and removed the killstreaks, with added game modes. The game mostly stayed the same as it is today.