When Batman rips the masks off The Joker's henchmen, they were facing him, meaning that when Batman held their masks, the faces of the masks should've been facing him as well. However, when he held their masks, the faces on the masks were facing the camera, away from Batman.
In this episode, The Joker wears a sort of bubble-helmet instead of the typical gas mask and his henchmen wear protective masks which look like clown masks. At other times in the series, his henchmen wear regular gas masks when he's using his standard laughing gas.
When Alfred talks while holding the drawing of the bath, the top part of the drawing briefly disappears.
The Joker stabs the barrel Batman's in six times in all directions, yet when it shows the barrel from the outside again all six holes are on the same side. Also, when Captain Clown tosses the barrel into the river, the holes briefly disappear.
This is the first episode in which Efrem Zimbalist Jr does the voice of Alfred, taking over from Clive Revil, Efrem still did the voice up until his appearance on the Justice League episode "Starcrossed, Part 3".
The Joker: Whoops! Looks like our air holes are water holes, too! Water shame!
Joker(dangling over the garbage incinerator) Batman! You Wouldn't Let Me Fry Would You?! (Batman thinks about it) Joker(whining) Batman!
(after Batman destroys his robot)
Joker: You...killed Captain Clown. YOU KILLED CAPTAIN CLOWN!!! Just for that...
The Joker: Justice is best served hot, Batman! You're gonna melt like a grilled cheese sandwich!
Joker: Look who's come to trash the place! Batman: A fitting setting for you, Joker. Joker: Ooh, I just love to get down and dirty! Okay, boys...it's playtime!
Bruce: What's wrong, Alfred? Aren't you feeling better?
Alfred: What's wrong, sir? I destroy a priceless Ming vase, and you ask me what's wrong?
Bruce: Don't worry about it. I'll just take it out of your salary for the next couple of years.
Alfred: Very well, sir.
Bruce: Alfred... April Fools'.
This is labeled episode 4 on the Batman: The Animated Series Volume 1 DVD.
This episode along with "On Leather Wings", "Christmas With The Joker", "Nothing To Fear" and "Pretty Poison" was released on DVD as Batman The Animated Series: The Legend Begins.
When Batman is chasing the Joker near the end of the episode, a variant of the 1989 Batman movie theme plays.
The Jewel of the Nile
When Joker and his goons exit from the submarine to rob Gotham City, Joker says: "When the going gets tough, the tough go shopping!". This is a reference to Billy Ocean's music "When The Going Gets Tough, The Tough Get Going." which was the theme song from the 1985 film "The Jewel of the Nile", staring Michael Douglas, Kathleen Turner and Danny DeVito.
At one point, The Joker tells Captain Clown, "Well, Captain! This looks like the start of a beautiful friendship!" This is a reference to the famous "Louie, I think this is the beginning of a beautiful friendship" quote from Casablanca.