Flyer on Ron Engelman studio window work is work event held on Saturday March 9th however in 1993 March 9th fell on a Tuesday.
In the episode the ATF is shown shooting penned dogs, then there is a general flurry of mostly-ATF gunfire that starts the battle. There's no compelling evidence the ATF fired first or the gun battle was simply a mistake. There is documentary evidence (video) and testimony both from agents and journalists there to cover the event that the Branch Davidians opened fire as soon as the ATF began to demand they all come out over bullhorns.
When the siege begins, it is a nice sunny day. However, on February 28, 1993, it was overcast and starting to rain.
The name of the ATF operation was Trojan Horse. The code word to signal the operation is a Go was Showtime. It was not ever called "Operation Showtime" which is the actual name of the episode.
When Gary Noesner leaves the FBI workout room, supposedly in Washington D.C., the distinctive large rounded adobe building behind him is the New Mexico state capital in Santa Fe.