The coffee Alfred serves Bruce at the end is not steaming.
When Riddler burns his costume, he was wearing his purple gloves, but after he throws his green jacket into the fire, his gloves disappear altogether.
The Riddler taunts Batman with a riddle at the beginning of the episode about robbing an antique store, but after Bruce sees the report on television later on and remembers the riddle, his memory of the Riddler saying the riddle is completely different to the point that the Riddler laughs tauntingly, which he did not when giving the riddle.
In this episode's title card, "Riddler's Reform" is misspelled as "Riddlers Reform."
The antique dealer claims a Ming vase from the 3rd century was stolen. This is not possible, the Ming dynasty was from the 14th to 17th century. 1100 years after the 3rd century.