"Friends of the Waynes though not as wealthy, their memorial ward keeps Gotham healthy."
Location: Eliott Memorial Hospital
Just find a good vantage point and scan the hospital's sign.
"The League of Assassins stuck blades through hearts, now they impale each other's art."
Location: Alley, near the parking building in Kingston.
Find the fenced alley with burning barrels inside. Examine the The Demon's Head poster on the wall.
“A former warden who had a Strange turn, his appointment as mayor was a cause for concern."
Location: Lacy's Dept Store
Head to the alley beside Lacy's Dept Store, where the “Sports Bar” signage is lit up. Look for the faded poster of Mayor Quincy Sharp
“Disarming, charming, quite the inquisitor. She'll pull back the vale, whoever her visitor."
Location: Rooftop of the Gotham Tonight building
Get on the rooftop of a nearby building and scan the Vicky Vale Show signage.
"Are you suffering from a mental split? Take out the trash before you defend it!"
Location: Near the Botanical Garden
Scan the Hells Gate store beside the Ocean Master Sushi restaurant
"A natural cure for Scarecrow's doom, your savior's gone but still in bloom."
Location: Botanical Garden
This will only become available after Poison Ivy sacrifices her life to clear Scarecrow's toxin. Get to the spot where she disappeared and examine the red flower on the floor.
"The Prince of Gotham sits high in his tower, yet this picture recalls a happier hour."
Location: Wayne Tower
Get inside the penthouse office, where you visit Lucius Fox in the story. Scan the Wayne family portrait on the wall.
"It doesn't take much to tame a Cat, make them wear this, and then call the bat."
Location: Orphanage
You have to scan Catwoman's explosive collar. If you haven't rescued her yet, you can scan it on her neck. Otherwise, you have to find it on the floor of the final exam room where she removed it.
"You forced this contraption over my brain, I'll reward you with punishment, debasement and pain."
Location: Orphanage
In the final exam room where you have to solve the last puzzle, there's a panel nearby that you can hack with your RHD. This will reveal a secret room inside. Scan the helmet on the table to solve this riddle. You may have to enter first-person mode by pressing R3 to properly scan it.
"The highest building in Arkham City, A Strange man worked here, who took no pity."
Location: A good vantage point overlooking Arkham City, which is located SE of the island. One good spot is the Wayne Tower. You may have to enter first-person by pressing R3 to properly scan it.