Only one of the "iguanas" featured was an iguana. The other lizard was a bearded dragon. The two species are not related and come from opposite sides of the world (iguanids originate in the Americas, whilst the bearded dragon originates in Australasia).
After blackmailing Renaldo Hayes and asking him to shave points in Lousiana's upcoming game with Texas, Terence meets with his bookie and bets on Lousiana - he should have said he was betting on Texas, which did end up being the winning bet.
When McDonagh arrives at the RTA involving the alligator there is a red pick-up truck in between the two lanes of freeway traffic. Then, when he asks Lt. Stoyer to do him a favour, the truck is not there.
When McGonagh blackmails football player Renaldo, Terrence dangles his handcuffs from his finger with the bottom cuff unshackled. Moments later, when the shot returns to Terrence, the bottom cuff is shackled.
After the shoot out with Big Fate's crew, Dave Jacobs's soul gets shot again. When he falls down from dancing his arm is underneath and behind him, but in the next shot his arm is tucked underneath him out of sight.
When Lieutenant McDonagh is driving with the witness to Biloxi he crosses the Mississippi River over the GNO bridge going the wrong direction. The view of the twin smoke stacks (also visible in Get Shorty) indicate he is heading to the west bank of the river. The only non-circuitous route back to the east bank would be via ferry routes that were not restored at that time and run through St Bernard Parish.
Nicholas Cage's character bets several times on college football games featuring Louisiana. The state has several universities with football programs, however there is no Louisiana University. There is a Louisiana State University (LSU) but they are never referred to as simply "Louisiana".
The film is set "six months" after Hurricane Katrina, putting the action in the movie occurring sometime around February 2006. In the film, Terence McDonagh continually bets on college football games, though in reality the football season is over by the time the action supposedly takes place.
For the bet on the "Lousiana"-Texas game, Louisiana is a 6 point favorite and McDonagh is betting ON Louisiana which means he expects them to win by MORE than 6 points, not less. Had he wanted the score to be less than a 6 point spread he would have bet on Texas.