During filming, animal rights activists showed up with the intention to make sure all the fish were treated correctly. After viewing the script, and realizing that the title of the film was really more about cheating 'fish' than actually shooting it, they left somewhat embarrassed.
To research their roles as conmen, both Stuart Townsend and Dan Futterman spent time flogging perfume from a suitcase in London's busiest shopping area, Oxford Street.
In the scene where Dylan picks up a toaster from a dumpster, all the extras (all of them males) can be seen pushing prams.
In the scene where the two con men install loft insulation, it was shot on a real street in England. The exact same trick had been pulled off two years earlier on this same street (using enough insulation for one home and then transporting it to the next using the adjoining attic) and is where the director got his inspiration.