After Wildcat and Green Arrow's fight, during the close up on Roulette as she goes on about the millions she is going to make, the chain links that are apparent behind her on the left side of the screen are missing entirely from the right side, although from other shots in that scene she is clearly fully surrounded by the chainlink dome.
Green Arrow's hat gets knocked off while fighting Wildcat, but it's not seen for the rest of the episode, on the ground or anywhere else.
The scene in which Green Arrow changes out of his civilian clothes has several errors. Previously he wears a turtleneck shirt underneath a suit jacket. He turns his back to Black Canary while they change, but he removes both the jacket and shirt by pulling them down over his shoulders, and he suddenly is wearing a button-front shirt. As the sleeves come down you can see his elbow-length Green Arrow gloves although he was previously barehanded. Also his quiver just appears, although it is clearly too large to fit under his clothes and there's no indication he left the building to get it and came back.
After Green Arrow drops his quiver as he enters the ring, it appears once or twice but otherwise disappears the rest of the time.
When Black Canary hops in and confronts the thug leader, his two goons are standing about 5' behind him. Then she jumps down, throws the leader, and they're in the same positions but suddenly much further back, and she throws the leader to where he was just standing relative to the other two.
When Canary "screams" the truck, the leader is driving. Then the van falls over on the driver's side and the second it skids to a halt, the leader instantly climbs out and falls to the ground. He would have had to climb over the passenger while the truck was still skidding to do that, which seems impossible.
When the truck leaves the crime scene, there are only two guys in the cab. Then it skids to a halt with no indication anyone flew out of the rear. But in the next shot there are four guys laying in front of it. Where'd the other two come from?
When Black Canary and Green Arrow first start fighting, they're both on the walkway with Black Canary right behind GA. Then GA shoots the two goons with a bolo-arrow and there's a side shot, and Black Canary is nowhere to be seen, behind him or anywhere else.
When Green Arrow fires the net arrow, Atomic Skull is in the lead. But when the group breaks out, Tracer is in the front using his wrist-cutters and Atomic Skull is behind him. Then when the villains start walking again, Atomic Skull is back in front.
Black Canary: Most people, after they sold the company for three billion, would just kick back and relax.
Green Arrow: I'm not most people. Besides, after taxes and the lawyers are through with you, you're lucky if you see a billion and a half.
Black Canary: My heart bleeds.
Wildcat: Just sit tight – I'll be there in ten minutes.
Black Canary: Would those be real minutes, or Wildcat minutes?
Green Arrow: Care to join me for a cup of coffee?
Black Canary: Yeah.
Green Arrow: Good - you're buying.
Green Arrow: At least now I understand why you brought me along. You didn't need Green Arrow - you just needed "green."
Green Arrow: Uhhh, there's no place to change.
Black Canary: Right here will do. (Green Arrow glances over his shoulder) You drop something?
Green Arrow: I thought that was just you pretending again...
Black Canary: What's that supposed to mean?
Green Arrow: Like all that flirting you did up at the Watchtower. The way you acted interested - to get me to come with you.
Black Canary: Who said that was pretending?
Black Canary: You know, that was an incredibly stupid thing to do. Not to mention arrogant, pig-headed, macho... and very, very sweet.
Black Canary: You happy punching the bag. or you want to go a few rounds with me? (Green Arrow stares) I am talking about sparring.
Green Arrow: That'd be nice, too.
On first airing, clips at the end are from "The Once and Future Thing: Time, Warped (2)" and the upcoming "The Ties That Bind".
Kin Shriner reprises his role of Green Arrow. Virginia Madsen, who had previously played Dr. Sarah Corwin in "The Brave and the Bold", plays Roulette here.
Other Leaguers that appear without dialogue: J'onn. None of the seven regular are credited this episode.
No change for the season 4 opening credits, which use the same montage of shots as in the last few episodes of season 3, except in the part with Black Canary is now using her sonic scream instead of standing there.
Thug: Nice guy to have around
The thug that Canary and Green Arrow buy tickets to MetaBrawl from looks remarkably like the Sacha Baron Cohen character Ali G.
The Cat and the Canary was a spooky-old-house stage play by John Willard, which has been filmed several times. The two most notable versions are Paul Leni's 1927 moody silent film and the 1939 remake which played up the comedy relief and made a star of Bob Hope.
The basic plot centers around the death of millionaire whose surviving relatives gather several years after his death to hear the reading of his will. A sole heir is named, but due to a streak of insanity in the family, a second will has been made in the event that the primary heir becomes insane. Warnings from spirits predicting death and the escape of a homicidal maniac ("The Cat"), sets up a night filled with murders, mysteries and intrigue. Although no discernible connection between the play/movie and this episode can be seen, the title was probably chosen for its literal reference to two of the heroes featured in this story.