When the time machine crash occurs, the time machine is damaged, because John Titor didn't calculate the co-ordinates correctly, so she can't travel back in time, ergo, Okabe can't go with her, and thus he can't scream. But in case of screaming, it was Okabe who went back in time, so the time machine landed correctly, ergo, no crash happened.
Despite this, the first episode shows both of them happening same day.
Aren't these two events contradicting each other?
If I get your question correctly, then the answer is NO. Those do not contradict each other because
The events you described above (first half of episode 1) happens in the beta worldline. In the beta world line the time machine is complete - hence there was no coordinate error and the machine did not crash. The time machine only crashed on the alpha worldline.
I hope that answers your question.
I know this was asked a while ago but I have to say this.
You probably forgot, since it was all the way back in episode 1, but Okabe does see the machine on the roof... not crashed, and hence he hears the scream. It's only after he leaves the building and sends the first demail that he sees the crashed "satellite".
I just finished the anime last night. I also rewatched the last episodes (22,23,24). At the last time I watched an ep of the anime, I noticed that there's a relevance of the events that happened in ep 24 and 1. In what I think. Okabe saved Kurisu by piercing himself for the blood pool so that the present Okabe (talking about the ep 1) will see/mistake her as dead in the first episode.(re watch from ep 24 to 1 to see the connection) The scream in ep 1 was definitely Okabe's (the Okabe from ep 24 when he pierced himself). Although it also doesn't really make sense to me on how the D-mail was sent to Daru in ep 1. Causing Kurisu not to remember meeting Okabe. And herself being alive (reffering to ep 2)
After thinking about stuffs regarding the REAL plot of the whole anime series. I realized that in the first episode, Kurisu weren't really dead. Okabe in the first episode mistook her as dead, which Okabe in the ep 24 exactly wanted. The first D-mail which Okabe ( 1st ep ) sent to Daru ; Seems someone stabbed Makise Kurisu. ( I forgot the exact words) That caused the "misunderstanding" Wherein, if Okabe went back to the time where the D-mail/Phone Microwave didn't exist, Kurisu would be dead, which wasn't.
It's a pretty interesting topic, I'd love to hear and see your opinions regarding this discussion. Especially those who just finished the one of the greatest anime ever, welcome to the fandom ^^
Note: If anyone have corrections for my post/theory and stuff , feel free to reply
The scream you mentioned was BEFORE Okabe sent a text message.
The crash you mentioned was seen AFTER Okabe sent a text message. (and for clarification, the time machine didn't crash into the wall, it appeared there. It wasn't this "crash" which damaged the time machine either, it was the later rain storm)
