I'm sure most of you have looked at the "Goofs" pages on IMDB. They're full of "crew reflected in car door" and "Actor's left lapel inverted in Close-up shot" kind of notations. Its actually kind of a miracle that every movie isn't full of these mistakes from beginning to end. There are millions of tiny details to keep track of. The Script Supervisor actually makes notations about things like the length of a cigarette when a specific line is delivered, or how much iced tea is in the glass and stuff like that. That's in addition to keeping track of what lens is in use, any filters on the lens, who is moving from left to right and vice-versa, and on and on and on. Yeah, this is a job I wouldn't want.
Anyway, those are the types of things that come up while you're shooting. There's a bunch of other details we try to deal with during pre-production. I get to sit through tons of meetings where we're discussing stuff that either relates to me directly, tangentially, or not at all. (I'm pretty good at faking an in-coming phone call from somebody I've been trying to reach for days!)
One of the most common things we meet about is weather. Will the leaves be green enough by the time we start shooting, or brown enough or whatever. Other than trying to schedule exterior scenes early or late in the shooting schedule, this isn't a subject we've got a whole lot of control over. But that doesn't mean the Director won't try. On one movie, the director actually had a long conversation where he wanted to use Agent Orange in NYC. "We'd just spray it on individual trees. It's not like we're going to just indescriminately spray it over the whole city." Another Director wanted the option of painting leaves brown and having a truck-load of dead leaves to be spread on the ground. This conversation was resolved after an hour of back and forth when the Producer proclaimed, "We're not making a movie about fucking leaves." (The prop master was told to always have a bag or two of dead leaves on hand.)
When we made Paradise, the big problem to be solved was The Flop Factor. If you've never seen the film, Don Johnson owns a shrimp boat and there's some scenes of him bonding with Elijah Wood while out shrimping. We couldn't just actually put out the nets and catch shrimp, because shrimping season hadn't opened yet in South Carolina. In fact, the only reason we had any shrimp boats available to us was because shrimp season hadn't opened yet. (Incidentally, shrimp season in South Carolina opens when someone from the Fisheries Dept. takes shrimp samples from some spot in the estuaries and determines that they're big enough to start shrimping, so we didn't have any specific date that we knew we'd lose the shrimp boats to their actual purpose.)
So, anyway, we had lots of meetings to discuss what would come pouring out of the nets when we dumped them on the deck. It was decided that it would be mostly dead fish and frozen shrimp and other stuff bought from a seafood wholesaler. But, there had to be something live and jumping around when we dumped the nets...The Flop Factor! I can't tell you how many meetings I sat through that returned to trying to come up with some scientific formula for determining what percentage of the seafood had to be live to have a sufficient flop factor.
On another movie, we were shooting in Toronto, but we were doubling it for New York. The Production Meeting came to a screeching halt when the Director said, "Ya'know, I've noticed that all the squirrels here are black. Are there black squirrels in New York?" Well, everyone at the table other than me was from L.A. or Toronto, so all eyes turned to me. Now, I'm pretty sure I've seen some black squirrels in NY, but mostly our squirrels are gray, so I said, "Yeah, some of the squirrels in NY are black." I thought that would answer the question adequately and the meeting would get back on track, but the Director was fixated. He follows this up with, "OK, Nathan, but how many of the NY squirrels are black?" Clearly, we had left my area of expertise, but I was the only one at the table who might even have a clue and the Director wanted to know. After pausing a moment, I said, "Seventeen. We have seventeen black squirrels in NYC." Everybody seemed satisfied with this answer and we moved on.