It could have, if he threw it before he got out of the mini cab, they were focussing on him at that stage.
I thought it had hints of some things being covered up without doubt, but I don't think anything was particularly convincing, and the witness that saw the gun taken from the taxi was very unconvincing (even to a jury), and from the footage a long way away to see it clearly.
Also the man who shot him clearly feared for his and others lives, put yourself in his split second decision, would you have shot, or waited to be shot ? Its a no brainer for him, the forensic expert evidence about what Duggan did, and where the shots hit him, were enough for him to shoot.
A very good documentary, but hard to draw any conclusions for me.