According to Bob Woodward's account in "All the President's Men" (and in the film as well), his call to Howard Hunt on June 19, 1972 (which resulted in Hunt famously blurting out "Good God!") was made to Hunt at his office at Mullen & Co. In the miniseries, the call is made to Hunt at his home.
A very brief shot prior to the bail hearing before Judge John Sirica shows the front of the "E. Barrett Prettyman U.S. Courthouse in DC." Prettyman was a well known US Court of Appeals Judge who died in 1971. But the courthouse wasn't named after him until 1997, long after the Watergate legal proceedings.
An Air France Boeing 747 is seen landing at, presumably, Washington National airport. Washington National cannot support large aircraft such as the 747. Furthermore, in 1974 there were no international flights landing at the airport, and Air France did not operate there.