We're told there was a loud argument Tuesday on the Boston set between David and Jennifer, and it started over a scene. The eyewitness says David started screaming at her ... it was was ear-piercing and laced with profanities.
A rep for the movie's studio -- Fox 2000 -- tells us yes, there was screaming, but it was all method acting. David was just getting J. Law amped-up for a scene in which she screams at someone.
But it doesn't end there. We're also told Miramax honcho Harvey Weinstein showed up on the set Wednesday to say hi to Jennifer, but David ordered him to leave. Harvey got as far as the makeup trailer before getting booted.
The studio rep says Harvey was told Tuesday things were moving at warp speed and his visit would be a distraction, but he showed up anyway ... unannounced.
And the eyewitness tells us a major exec for Fox was reamed out by David because she was trying to defend the line producer who David wants to fire. The eyewitness says it got so bad the exec started crying. The studio rep says that's ridiculous ... there was a "heated" argument over the line producer, but she didn't cry.
You may recall David's nuclear argument with Lily Tomlin during filming of "I Heart Huckabees."