Why was Vader talking about "Rebel transmissions" in Episode IV when he saw the data tape being passed in Rogue One?

Question

In A New Hope, Darth Vader on Tantive IV says: “several rebel transmissions were beamed aboard this ship from rebel spies…”.

Except that, in Rogue One, we see that the plans were NOT beamed onto Tantive IV - it was docked inside Mon Calamari flagship, and the plans were physically sneaker-netted through a door from one rebel to another as a data tape - witnessed by Darth Vader!.

Vader clearly knew what the tape was from the novelization:

The voice of a stormtrooper spoke to him through his comlink. “A data tape was recorded on the bridge just before we boarded. No sign of it here.”

[...]

The security door opened a mere crack and rebel hands shoved the tape through. Vader reached through life and matter and air and by will alone he pulled. He fueled his will with rage and fear and need. It was enough to tear the rebel from the door and drop him at Vader’s feet.

But it was not enough to claim the tape.

He grasped the rebel sprawled before him by the throat, lifted him and stared at him through bloody lenses. “Where,” Vader demanded, “are they taking it?”

Is there an explanation for this discrepancy?

Answer 1

Either he thought Tantive IV was an escape vessel, not its own ship, or he didn't see the data tape

Pablo Hidalgo has been asked this question several times on Twitter (once by yours truly), but his most helpful response is probably this long Twitter thread from late December 2016; in it, Hidalgo pretty much confirms that this is an inherent contradiction between the film and the novelization:

@TheDonkeyDrip "As particle bolts shot toward him, he watched a data tape pass between desperate soldiers."

@pablohidalgo Yeah, it has the stormtrooper tell him as well. I was referencing the movie.

He does provide a rationalization for this earlier in the conversation:

@TheDonkeyDrip but then why is he so adamant about "beamed transmissions" if he saw the physical data tape?

@pablohidalgo Did he see it?

@TheDonkeyDrip The official novelization says he did.

@pablohidalgo Novel also has him view the Tantive as an escape vessel of the cruiser. Cuts on either side of semantics.

The passage he references is probably this one from the novel:

"Where," Vader demanded, "are they taking it?"

The reply was a strangled whisper. "Away from here," the rebel said. "Away from you."

Vader clenched his gloved hand until the man's neck snapped. Then he tossed the body aside. He activated his comlink and barked to his stormtroopers, "Find their escape vessel."

^{Rogue One: A Star Wars Story - Official Novelization Epilogue}

So you have two options:

1. He didn't see the tape. Wouldn't be the first time a novelization got something wrong; they're normally based on early drafts of the script, so perhaps this was an error that just got caught too late to fix in both versions. As Hidalgo reminds us:

   

   Think of a novelization as an adaptation of canonical events.

   Because of how and when they're written, there will always be differences.

   In cases of contradiction, defer to the movie.

2. He didn't see Tantive IV as an independent vessel. This is an admittedly weak rationalization, but if Tantive IV is an extension of the Profundity, then Vader's statement makes perfect sense.

Answer 2

There certainly were transmissions from Rebel spies on the planet's surface to a Rebel ship in orbit.

It is true that the transmission was to the rebel flagship, and from there it was brought on a data tape to the blockade runner in one of the flagship's hangar bays.

There are a couple of plausible explanations:

1. Vader simply does not care about such details. There was a rebel transmission, and the data from that transmission ended up on the blockade runner. His goal is to intimidate the Rebel officer, not provide an accurate technical report.

2. Vader is angry with the failure of the Imperial forces on the planet's surface to prevent the transmission. It would be in character for him to focus on this instead of

his own failure to stop the Rebels from handing the plans through the airlock

because as we all know, Anakin/Vader is not very good at taking responsibility for his actions.