Jesse Eisenberg's pizza delivery boy character is forced to rob a bank with a bomb tied to his chest in the crime thriller.
The family of 46-year-old pizza delivery man Brian Wells, who died in a similar case in 2003, have criticised Fleischer for drawing on the real-life event.
Fleischer has denied that the script refers to the Wells case and said that it did not provide any inspiration.
He told The Huffington Post: "For me the best reference was Fargo.
"It's another misguided crime plot where somebody comes up with a bad idea and then, as it goes down, it gets worse and worse and spirals out of control and has dire consequences.
"Ours is definitely a more positive, funny, uplifting version of that."
Fleischer added that "[the real-life incident] doesn't really relate to that story other than the fact that there's a bomb strapped to somebody's chest".
30 Minutes or Less co-stars Aziz Ansari, Danny McBride and Nick Swardson as the gang involved in the robbery.
Fleischer is best known for directing Zombieland, which also starred Eisenberg.
Eisenberg has previously said that he would be keen to make a sequel to the comedy horror film.
30 Minutes or Less is released in UK cinemas on October 16.
Watch the trailer for 30 Minutes or Less below: