In PAYDAY: The Heist, you may find weird names on name plaques or the like. This was during Overkill's "Lucky 200" event where the first 200 people to show proof that they reached the max rep level of 145 would get their names in the game. These names also pop up in PAYDAY 2, but this is a coincidence due to the developers reusing level assets (crates, notebooks, etc.) from the previous game.
In a similar vein, the Counterfeit secret event resulted in two plaques on the walls of the secret vault that have the names of players that contributed to the event in some way.
In Bain's Guide (included in the Steam version of PAYDAY 2 if you pre ordered the Criminal Career Edition), there are a few subjects that take a friendly jab at the fans that complained heavily about certain things; in the section of the guide that describes the ammo bag, you can see the word "clip" typed out and then typed over to cross it out, replacing it with "magazine" and then circled in red while noting "Never forget!" This is a jab at the player base that loudly complained about how the developers used the wrong terminology. The section describing Crime.net also takes notice at how everyone complained about it (feeling like the system was too restrictive on what heists they could play) and that people should stick with it since Bain promises good things will come out of it.
Artist Disillusionment: Came very close on more than one occasion. When the secret in the first game was revealed, flame wars broke out and people also bashed Overkill for making the event too hard. Overkill responded by saying they may have to think about how they will interact with the community in the future, but everyone on both sides cooled off and everything was resolved. The sequel, however, made the the trope more apparent when fans massively complained about nearly everything. An Overkill developer had to openly tell everyone to stop acting like jerks towards them and the rest of the community because it doesn't make the community look good overall.
Sadly, the fans trashed Overkill even more, still accusing them of withholding content for DLC and they even blasted Overkill for scolding them (the fans), even though the fan base threw the first punch.
The fact that 3 DLC packs (one free and two purchasable ones) seem to be only available for PC, as of now, the delay and no feedback from Overkill of when consoles will see the light of the promised DLC, have created quite a few complaints.
Recently however, Overkill has made talk of a patch that will bring the console editions up to date with their pc counterpart, excluding paid for dlc
Easter Egg: A small sign near the entrance to the gym in Mallcrasher in Payday 2 lists off several perks of joining, such as the first month being free. The fourth? "Another Selling Point".
Fan Nickname: "Old" or "British" Hoxton from PAYDAY 1 to differentiate from the current Hoxton that is in PAYDAY 2. The old Hoxton references himself Old Hoxton in the Christmas album as well.
Mean Character, Nice Actor: Hoxton in the first game is an Evil Brit who will yell at civilians at the top of his lungs while killing cops in cold blood and swearing at them in British profanity. Pete Gold, the voice actor behind British Hoxton, is very down to earth and actually tries to not swear in real life due to him having a child. Pete Gold, who wasn't called back by Overkill to voice Hoxton in the sequel, was actually surprised and humbled to hear that fans loved his take on old Hoxton so much that they created a petition to get him back for the role. Pete has even recorded several quick lines under the Hoxton persona for fans that requested it.
Meme Acknowledgment: A glitch in the beta of PAYDAY 2 caused a mask pattern called Electric Center to be awarded to players at the end of a heist nearly every single time, which caused a Memetic Mutation in the community. Bain in episode 4 of the web series references the Electric Center.
In PAYDAY: The Heist, there was a mission with a phone that rings. There is no way to answer it. During the secret event, trolling players would ask, "Have you tried answering the phone?" whenever someone tried to come up with a solution to solve the secret. When you first play the safehouse in PAYDAY 2, a phone rings and your objective is "Answer the phone." When you walk up to it, it stops ringing, and Bain, who is watching your every move, says, "See? You didn't even have to answer the phone!"
Becomes a Hilarious in Hindsight moment when you realize that the No Mercy heist from the first game had you answering the phone and day 2 of Framing Frames in the sequel also has you answering the phone.
Phones can also ring (randomly) during certain heists, such as any Bank Heist or Jewelry Store/Ukrainian Job. Still can't answer them.
The Christmas heist, GO Bank, has answering the phone and patching Bain through as an integral part of a stealth run. Phone calls can range from the harmless (someone calling because they watched a movie with a bank robbery, and want to move their money to bank that doesn't get robbed) to the potentially disastrous (GENSEC calling to say they are sending a team of guards [with pagers!] to check out the bank.)
Official Fan-Submitted Content: The PAYDAY 2 skill calculator. OVERKILL endorse it as it not only significantly helps plan upgrades, but it gives exact figures on boosts and bonuses.
Taken a step further by Overkill where they basically took the entire thing and merged it with the game, making the fan content part of the game officially now.
Urban Legend of Zelda: PAYDAY 2 has some meth cooks in day 1 of Rats that get shot by the Mendoza gang when you enter the house. Many people say that if you're fast enough, you can save the cooks and cook the meth without the cops coming. It's all bullshit due to the death of the cooks are completely scripted; if you reach the house fast enough, you can see the cooks instantly slump over without any of the enemies shooting them at all. Not only that, but Bain also tells the crew that the cops were watching the house the whole time, so stealth is impossible to do.