[...]
"Firecracker hit me in the back of the head" golditch
"they set gas bombs as they were leaving" glasses girl
"thought kids were throwing fire crackers into the theater" ostergaard
"they threw gas bombs into our theater" fedelli
"my ears were ringing" golditch
"it was louder than it hurt" golditch
"I saw an explosion" ostergaard
"My leg got really hot" walton
"2 pops and a big cloud of smoke, then another pop, and more smoke... people were saying it could have been fireworks... no one knew there was a shooting in theater 9" fedelli
You have quotes from five people. How many were in theater 8? I can only assume that these witness quotes are the absolute best you have to support your claims (if they are not, let me know). So far you have statements from a tiny minority of witnesses. Let's look at them, anyway.
Golditch was hit in the head by a bullet or shrapnel, if I recall. Here is an experiment. Tap on your head. Now tap on your knee. The tap on the head sounds remarkably louder doesn't it? If that was a bullet strike, imagine how much louder. Also, the ringing could be due to injury rather than noise. I do not know the exact injuries, so that is a possibility I cannot rule out. Every single part of his testimony is perfectly consistent with being hit by a bullet/fragment.
Walton says her leg got hot. This could mean just about anything. If your leg falls asleep, it can feel hot as feeling comes back. If she hit or scraped her leg it could feel hot. Or heat could be from a vent. The subjective sense of heat alone could be anything. If it was from an explosion and she was close enough to feel the heat, there should be other signs of this, injuries, and she should have bloody well heard the explosion. Do you have more information? Do these other signs exist? If not, other explanations are more likely.
Fedelli heard pops, not booms or explosions, and saw gas and/or smoke. The pops fit gunfire next door, which we already know happened. So we only have to explain his smoke testimony. "Glasses girl" said gas bomb, which I assume means she saw smoke? Again this could be from vents.
That leaves Ostergaard, who says he saw an explosion, though describes the sound as like firecrackers. The sound again is likely gunfire next door. Then a flash and smoke in the stairwell. Smoke could be from vents. Flash could be a lot of things, from the movie, spark from bullet strike, breaking light bulb.
Notice, I have assumed that the witness are accurately reporting what they witnessed, that their memory is not faulty, and that the quotes are not out of context. Almost all of it can be easily and better explained without explosives of any kind in theater 8. You have at best one witness from the entire theater who saw something explosive-like, but describes a decidedly unexplosive sound.
If almost everyone in the theater saw or heard an explosion, then you would have something. Without the testimony of the rest of the people in that theater, I provisionally assume that these isolated statements are either misinterpreted or are outliers specifically selected because they are the absolute best for making the case for conspiracy, which turns out to be not very good.
I will end by pointing out I am not an expert in any of this, and have researched this "theory" only a little. I welcome any corrections.