I came across an old essay on the Harry Potter Lexicon dated 17th January 2001, written after the release of Goblet of Fire when many details about Voldemort's attack at Godric's Hollow were still unknown. Intriguingly, it floats the idea, on the basis of what is written in the first four books, that Voldemort couldn't have attacked both Harry and Lily/James.
According to JKR (Diane Rehm show, 10/20/99), "Voldemort killed James and Lily, then tried to kill Harry." This is clearly what she intends. It is not, however, what it actually says in the books. This page discusses what the actual text states and what that would mean. Clearly, JKR doesn't intend this to be the way the story goes. But this IS the way it's written.
Everything that was known for sure about the events at Godric's Hollow in 2001 was based on the voices Harry hears when in the presence of a Dementor, Voldemort's own first-hand testimony of that night after he returns and the Priori Incantatem in the graveyard. Yet the Priori Incantatem contains a key omission - the Avada Kedavra cast at Harry by Voldemort (one of the most important events in the whole story!).
The article's summary of the Priori Incantatem is as follows:
Cruciatus Curse cast on Harry by Voldemort a few moments before (comes out as screams), June 24, 1995
conjuring of a magical hand to replace the one Wormtail cut off, cast by Voldemort after regaining his full body, June 24, 1995
Cruciatus Curse cast by Voldemort on Avery, June 24, 1995
the murder of Cedric Diggory with the Killing Curse, cast by Wormtail on Voldemort's command, June 24, 1995
Cruciatus Curse cast on Wormtail, witnessed by Harry in his dream, cast by Voldemort, exact date unknown, but somewhere around the last week of May, 1995
the murder of Frank Bryce with the Killing Curse on the evening of August 20, 1994, cast by Voldemort in his "ugly baby" form, from his chair in the Riddle House
the murder of Bertha Jorkins, exact spell inknown, cast by Voldemort, summer of 1994, some time before August 20
the murder of James Potter, exact spell unknown, apparently cast by someone other than Voldemort and probably NOT at his direct command, on the evening of or sometime after October 31, 1981.
the murder of Lily Potter, exact spell unknown, also apparently cast by someone other than Voldemort and probably not at his direct command, also on the evening of or sometime after October 31, 1981.
Since the attack on Harry isn't mentioned the writer logically concludes that the murders of Lily and James took place after the attack on Harry in which Voldemort lost his body, and that therefore Voldemort must have had an accomplice when he went to Godric's Hollow.
The evidence that we do have from the Priori Incantatem suggests that James and Lily were killed using Voldemort's wand AFTER Voldemort attacked Harry. After all, the last nine spells that wand cast included the ones that killed the Potters but DID NOT INCLUDE THE ONE THAT ATTACKED HARRY AND REBOUNDED ONTO VOLDEMORT. This mystery still remains, no matter in which order Lily and James came out of the wand. Who, if Voldemort was unable to cast a spell, killed James and Lily Potter?
We know from the later books, most notably from the description of the attack in Deathly Hallows, that this wasn't what really happened. Yet the Priori Incantatem gives that impression. To fit with the order of events in the other books the Priori Incantatem should have gone:
The murder of Bertha Jorkins.
The failed attack on Harry Potter using Avada Kedavra.
The murder of Lily Potter.
The murder of James Potter.
Yet it didn't.
There's no mention of the Avada Kedavra in the text, which moves straight from Bertha to Lily.
But already, yet another head was emerging...and this head, grey as a smoky statue, was a woman's...Harry, both arms shaking now, as he fought to keep his wand still, saw her drop to the ground and straighten up like the others, staring...
The shadow of Bertha Jorkins surveyed the battle before her with wide eyes.
"Don't let go, now!" she cried, and her voice echoed like Cedric's, as though from very far away. "Don't let him get you, Harry - don't let go!"
She and the other two shadowy figures began to pace around the inner walls of the golden web, while the Death Eaters flitted around the outside of it...and Voldemort's dead victims whispered as they circled the duellers, whispered words of encouragement to Harry, and hissed words Harry couldn't hear to Voldemort.
And now another head was emerging from the tip of Voldemort's wand...and Harry knew when he saw it who it would be...he knows as though he had expected it from the moment when Cedic had appeared from the wand...knew, because the woman appearing was the one he'd thought of more than any other tonight...
(Goblet of Fire, Chapter 34, Priori Incantatem).
No description of the Avada Kedavra there. And yet we know that Priori Incanatem reveals all spells, not just murder victims. Hence it produces screams to represent the Cruciatus Curse and recreates Wormtail's hand and the Dark Mark in ghost form. So the Avada Kedavra should have appeared but didn't.
Is this just an editorial oversight or is there an in-universe explanation?