It's not uncommon to watch an episode of a procedural and have counsel make an argument to someone on the witness stand, something along the lines of: "Based on the ballistics, isn't it clear that the defendant was the one who shot the victim?" In truth, no arguments are presented until the closing, after all the evidence has been presented. The presentation of evidence is a separate part of the trial and although counsel will often ask witnesses for their opinions or conclusions, they don't make any arguments or connect any of the dots until the separate closing arguments section of the trial. I think fiction tends to lump the presentation of evidence and elements of closing arguments together because - to be honest - the presentation of evidence is dry and tedious. It probably makes a courtroom scene more dynamic if counsel moves around and interacts with the witness and the jury rather than following strict, formal court procedure.

When physical evidence is preserved, it's typically placed in a paper bag or paper envelope and sealed. In order to review the evidence in court, the witness will put on latex gloves, break the seal on the bag, and remove the object inside so that it can be presented to the jury.In fiction (especially visual stories like those in movies and television), it's common for the evidence to be placed in plastic bags, although the reason that's not done in real life is because plastic is a chemical compound and there's some risk of contamination of the evidence. The authorities wouldn't want trace amounts of plastic chemical compounds to transfer onto, say, a murder weapon, and risk leading expert to other conclusions when they analyze it. I suspect plastic bags are used because they're more convenient; a scene in a procedural flows a little more efficiently if the prosecutor can hold up a gun visible inside a plastic bag rather than having to open a paper one and remove it.

Unlike procedurals where the judge is banging his gavel, declaring people out of order, and independently ruling on the things counsel and witnesses say, the judge in a real trial (albeit based on my very small sample size of one) is there to rule on the arguments and challenges that are presented to him. Throughout the entire trial, our judge merely ruled on motions brought up by counsel, clarified issues for the jury, maintained the schedule of the trial, and noted things for the record. In fiction, I think there's a tendency to make the judge more of an active participant in a courtroom scene, but the reality is that the judge is there to guide the trial's progress and make judgments on what others do, not take an active role in dictating who says what, if this or that is a good idea, etc. Generally, if opposing counsel doesn't lodge an objection, the judge doesn't make a point of intervening.