"Classic" Cars!
One of the funniest moments might have been unintentional!
When he's having his flashback to being a child, there are two 1950's-era cars in the foreground. But, everything else in the background are cars from that early 1980's time frame when the film was shot!
I. Drink. Your. Milkshake! [slurp!] I DRINK IT UP! - Daniel Plainview - There Will Be Blood