Revealing mistake: When Max writes down the code and hands it to Hercules, the paper is blank the entire time.
The Wax Max - S3-E20
Revealing mistake: In the tunnel of Love scene, one shot shows an axe being thrust down at Max. The axe is visibly blunt.
Revealing mistake: When Hymie is investigating the unconscious man in the shower, for some the reason the man is wearing underpants even though he is in a shower. Evidently for modesty.
Revealing mistake: When Purvis is about to go onto the field, it cuts to a close up of Purvis' face and you can actually see folds in the fake sky behind Purvis.
Revealing mistake: When Hymie does the high jump, when the film cuts to a shot of him clearing the bar, Hymie's hair is curly when it should be flattened down like when he took of and as he landed. It is obviously a stunt double.
Revealing mistake: When Max and 99 are rowing away on the Chief's inflated diving suit, you can see that the Chief is not in the suit and it is just an inflatable raft.
Revealing mistake: Siegfried uses the magnet to push the ship away from the island. However, you can see the scene is reversed; the steam from the ship is going back into the funnel.
Revealing mistake: When Max accidentally shoots the life raft with the flare gun, he visibly doesn't make a hole in the raft. It's likely it's ink or ash or another black material to look like the raft had a hole burned through it.
To Sire, with Love: Part 2 - S4-E21
Revealing mistake: When the tarantula is released into the room, the spider is a plastic model in its container when it's on Max's shoulder, and when they kill it with the horseradish.
Revealing mistake: When Max crashes through the wall in the prologue, you can easily tell it's a stunt double. You don't even need freeze frame to see it, as the screen freezes, stylistically fades, then the title sequence starts.
Revealing mistake: When Max and the other control Agents are old, you can see the powder on their faces used to make them look old.
