Plot hole: Harry tells Doc Ock that in order to find Spider-Man he must find Peter first. Doc Ock finds Peter with Mary Jane in the cafe and throws a car through the window straight at them, then later throws Peter against a brick wall. Any normal person would've been killed instantly (or very badly injured), and Doc Ock doesn't yet know that Peter is Spider-Man. Given that Peter is his only lead on Spider-Man, it makes no sense that Doc Ock would try to kill him.
Suggested correction: Doc Ock is being controlled by the arms. They aren't behaving rationally.
Creating a series of silly explanations for obvious plot holes never resolves them. These arms were not behaving irrationally. In many scenes they were shown to be very intelligent. A good example is the scene where they attack doctors who try to remove them from Doc Ock's body. Saying that they weren't behaving rationally is absurd.
He may not have been trying to kill Peter, he could've been trying to make more of a scene of his entry, so Peter would take him more seriously and tell him where Spider-Man was. He could've been thinking of it as a risk of killing Peter though, but his arms made him go crazy.
This is only a theory. Theories never resolve mistakes.
It's not a theory. When Otto is first giving his demonstration to everybody at his apartment, a woman asks if the advanced AI for the tentacles would make him susceptible to being controlled. Otto says that yes it would so he shows everybody the inhibitor chip that he designed so he would not fall under its control. After the inhibitor chip gets destroyed, it's seen that the tentacles have not only taken control of his mind by forcing him to commit crimes, but have slowly driven him insane.
This scene is much too confusing for many people. This entry is correct. This is a mistake.
If these tentacles wanted him to finish the experiment then they wouldn't make him kill the person who has valuable information for him.
The arms are influencing his thoughts but not controlling every part of him. Doc Ock still seems to have control when defending himself but they seem to work in tandem with Ock. The only time they work on their own is when he under anesthetic. As we don't see him before he throws the car, we can only speculate the arms were trying to hurt Peter by themselves.
It's a cool scene regardless man.
Killing Peter would probably send a message to Spider-Man as well, so Ock probably wasn't concerned about being gentle.
Plot hole: Dr Octo builds a new, bigger machine and it starts to pull the building in on itself, but it's so strong it also manages to pull all the metal from the streets as well, including cars. When Spiderman saves MJ, the metal cranes have somehow managed not to be pulled in or at least bent by this massive machine that made a building collapse on itself.