All items listed here can be obtained during your first time in the zone.
Joker Teeth #1, #2
As you head down the first hall, the lights will flash. Once they come up, move past the hanging guards to find the first two sets of teeth at the end of the hall.
Joker Teeth #3
When you wake up in the burning room, the next set of teeth will be to your right, in front of the stairs.
Joker Teeth #4
When you ascend the shaft with the first Joker thug, continue to the top. Use the Batarang to knock away the trap door, then grapple to an upper room. In here, grapple to the ledge, and exit to the left. Grapple up to an even higher room to find another set of teeth inside.
Joker Teeth #5
Once you ascend to the construction area, you'll crawl through a vent. These are at the vent's exit.
Red Son Cowl
Immediately after acquiring the Line Launcher, you'll zip over an electrified floor. On the other side, grapple to the high ledge and crawl through the vent. Use the Line Launcher to cross the gap up here and reach a WayneTech crate.
Blackest Night Boots
When you enter a room with two thugs across a pit of Joker gas, don't cross via the Line Launcher just yet. Instead, use the upgraded Gel Launcher to close the vents and drain the gas. Drop down and use the Crypto Sequencer to open a small room with a WayneTech crate inside.
Joker Teeth #6
In the very next room (above the library), drop to the lower area to spot these chattering about.
Before hopping through the gap by the flaming crossed beams, move left. Use the Crypto Sequencer to open the door, then use the Line Launcher to reach a ledge where a WayneTech crate lies.
Joker Teeth #7, #8
In the next room is a pit of Joker gas, but there are two sets of teeth inside it. Hop in or throw the Batarang to snatch them up.
Joker Teeth #9, #10
Your next task is to find the warden. When you enter the long hall with Joker gas below, you have two options. You can turn off the power to the gas a bit later, or you can deal with a bit of poison damage and grab the teeth from below.
After opening Joker's present, hop into the vent. When you emerge from the other side, use the Batclaw to rip down the upper vent cover. Up here is a WayneTech crate.
Joker Teeth #11, #12
You'll find these when you head through the other vent.
Joker Teeth #13, #14, #15
You'll spot these just before reaching the warden.
Joker Teeth #16, #17
In the basement, you'll fight a huge group of thugs. After the fight, grapple to the yellow ledge, shimmy right, and drop down onto the catwalk. There are two sets of teeth there.
One Million Chest
After obtaining the Shock Batarang, ride the elevator back to the previous floor. Now, drop back down the Joker's matching game and return to the elevator shaft. With the elevator risen, drop down into the shaft to find a WayneTech crate.
Joker Teeth #18, #19, #20
When you return to free the warden, you'll run into these while deactivating the electrical charges.
One Million Cowl
As you exit Administration, stop in the burning room. Grapple to the high left ledge, then turn right and use the Line Launcher to reach another area. Grapple through the series of ledges here to find a WayneTech crate.
As you continue to exit Administration, you can hit this switch with the Shock Batarang. Grapple into the shaft and head left. At the end, you'll reach a room with another power-up.