Are there unadvertised world interactions like shooting off locks to open doors?

Question

I just learned the other night that you can shoot the doorknobs off of wooden doors (as opposed to picking them, like the door to the shed in the mission Rats). Makes sense right? I just assumed that you weren't able to do such a thing.

Question: Are there any other unadvertised common sense things in Payday 2 like this?

I was just curious as I found this to be quite satisfying. Prior I kept thinking "Why can't I just bust the door down? I'm already caught there's no point in trying to be sneaky." and then my buddy told me about shooting the knob and I literally just dropped my head to my desk in awe.

Answer 1

I've compiled a list of what appear to be some unadvertised interactions. For all intents and purposes I'm defining unadvertised interactions & information as information that isn't regularly broadcast possibly resulting in the missing of helpful information.

• Doorknobs - As mentioned in the question, more information can be found here.
• Escape Van - Some missions, whether you're aware of it or not, have the escape van there from the very start. Many times it just leaves when you become detected. The Jewelry Store Heist is a prime example of this. It can be finished in about a minute thanks to this.
• Camera Security - Cameras no longer detect you if you've killed the guard in the security room (Some missions are not applicable to this, i.e. they don't have security rooms). This one is simple and partially obvious but for some reason it took my a while to figure out.
• Environment Matters - Your environment matters in some cases. Case in point: Park Escape Mission: The street without police blockades or SWAT vans is going to be the road the escape van shows up at. Noticing this allows you to take the loot to this location preemptively and escape smoothly.
• Extra Loot - More times than not there will be extra loot lying around during heists. It is up to you whether you find it worth picking up (usually is unless you're doing speed-runs). Example here.

Answer 2

• Opening Security Doors - If you somehow manage to make it around to the other side of a security door (which I've encountered in Nightclub and Election Day day one), you can hold down the interact button on the doorknob to open it immediately. If the door is currently being drilled from the other side, the drill will disappear and the door will open. However, if the drill is currently broken (yellow outline) or can be upgraded (blue outline) then you might need to do that first. Seems it can get in the way.
• Framing Frame Skylights - This is probably a more obvious one, but on day one of Framing Frame you can interact with the skylights (the ones which aren't quite closed). Once they're open, you can drop into the gallery from above. Be sure to land on something high up, because a straight drop to the floor is fatal. If there's somebody in your crew who has aced the Transporter skill (the one which lets you throw bags further), they should be able to throw the paintings high enough that somebody on the roof can catch them through the skylight. This should make it easier to get all of the paintings to the van, since you can just throw them across the roof and then into the car park at the far side. But watch out for guards.

Answer 3

• Server doors: In the heists where you have to hack a server and there are multiple doors which have to be opened, you can sometimes find the right one by listening to the sound made by the server itself (e.g. Framing Frame day 3, Big Oil day 2). In Big Oil day 2 if you are lucky the villa's shutters will be open, and that allows you to check immediately whether the server is in the room on the side where you spawn.
• Shutters: They count as walls but they can be shot through with a sniper rifle or Slug Ammo.
• Fusion reactor: The correct fusion reactor (Big Oil day 2) can be found by looking around the house for notepads.
• Hand Drier: (really) In Framing Frame Day 1, you can lure guards towards the bathroom on the right of the museum by crouching under the hand drier.
• Watchdogs day 1 escape: The escape van is triggered to arrive shortly after the 4th delivered coke bag, so it's wise to wait for all the bags to be close to the drop point before throwing them in the car. Moreover, by protecting the escape driver in day 1, the spawn in day 2 will be close to the bags instead of at the end of the pier.
• Watchdogs day 2 escape: The loot bags counted towards the final reward are both those thrown in the boat and those carried by the players. The pier where the boat will arrive is one of those where the ship didn't spawn.
• Go Bank Stealth: The escape sequence is triggered in different ways depending on the moment in which the alarm goes off. In order to trigger the sewers escape you'll have to throw at least 1 bag in the escape van. If the alarm triggers before securing the first bag, you'll have to wait for the plane. You can escape as soon as the first bag is secured.

Answer 4

• Medic bag - not only heals you, but also resets the number of times you can go into bleedout before going into custody. Source.

• Item physics - Some items use physics to a limited extent. In the safe house, you can melee boxes off the counters and shoot them down the stairs and hallway, for example. I haven't yet found a use for it, but I am keeping an eye out for things like being able to block line of sight to the critical point above your head or using it as a step to get onto a dumpster. (Now that I think about it, I wonder if maneuvering a box on top of a dead guard's head would keep witnesses from alerting. I hope not).