Look closely at the screen grab below, taken from the first-season episode "The Hungry Sea."

Excluding the neon loops at the top of the neon array, and counting down from the middle, there are sixteen rows of neon tubes. Robot builder Craig Reinbrecht, with his meticulous eye for detail, was the first robot builder to bring this interesting fact to my attention.

Now, look at the following screen grab from the second season episode "Wreck of the Robot."

Here, there are twelve rows of neon tubes.

Here is another view of the neon tubes from the first episode of the second season, "Blast Off Into Space."

The Loss of the Sixteen-Row Neon Unit

In the first-season episode "War of the Robots," the robot has the regular sixteen neon tubes in some scenes. In other scenes, not only are there only ten tubes, but the lower register of tubes is crooked. What happened? Examine these screengrabs:
 

In this shot from the clifthanger tag of "Ghost in Space" leading into "War of the Robots" ("Ghost in Space" scene 162), the standard sixteen rows of neon tube unit is present.	In this shot "War of the Robots" scene 178), an entirely different neon unit has been installed. There are only ten rows, the neon tubes are of a larger diameter, and the bottom rows are crooked.
In this shot ("War of the Robots" scene 172), we have a full frontal shot of the replacement neon unit.	In this shot ("War of the Robots" scene 206), from the last act of the episode, the normal sixteen-row neon unit is back.

The episode "War of the Robots"  was filmed between Monday 24 January 1966 and Monday 31 January. "Ghost in Space," including the teaser for "War of the Robots," had been filmed several weeks before. The episode filmed immediately prior to "War of the Robots" was "The Magic Mirror," but this is the only episode in which the robot makes no appearance whatsoever.

On Monday 24 January, the first day of shooting of "War of the Robots," all the scenes in which the sixteen-row neon unit appears were filmed. This included the robot's scenes in Act One of the episode (scenes 23 through 28) and the end of the episode (scenes 190 through 207), beginning with the action following the robot's creation of a smoke screen during his battle with the robotoid and ending with Dr. Smith polishing the robot's torso.

It may be helpful to remind the reader that  Lost in Space scripts were not filmed sequentially. Instead, scenes were shot according to the stage and camera set up. For instance, all scenes in an episode that take place on the upper deck of the Jupiter II with the actors in front of the viewport would be filmed one after the other, no matter where the scenes occurred in the script. This practice greatly reduced the time needed for set changes, lighting set up, and camera set up.

By the second day of filming (Tuesday 25 January 1966), the sixteen-row neon unit was gone. In its place was a poorly made temporary ten-row neon unit. The tubes were of a larger diameter, the lowest row of neon was crooked, and the rows of neon were unevenly spaced. The sixteen-row neon was never seen again. We do not know what motivated the crew to remove it. Presumably, it broke on the evening of Monday 24 January 1966 after shooting had finished for the day. Perhaps it broke while the crew were putting the robot away for the night. No documentation has yet been found to explain the loss of the sixteen-row neon.

The ten-row neon unit was used for the rest of the week. My research strongly suggests, however, that yet another neon unit, a new twelve-row neon unit, was installed on the morning of Monday 31 January 1966, the final day of filming for "War of the Robots." A hand-written note at the bottom of the production report for that day states: "Company Delayed 45 min (8:30 AM to 9:15) due to robot talking light going out." Filming began that morning at 8:00 AM. The first scenes to be shot were scenes 170 through 178, in which Will Robinson has just found the robot immediately after escaping from the campsite where the robotoid is holding the other crew members prisoner. In these scenes, Will tries to convince the robot to assist him in overpowering the robotoid and freeing his family.

Thirty minutes into shooting that morning, something happened to the temporary ten-row neon unit, and shooting came to a halt. This delay was considered important (and perhaps costly) enough to require additional explanation in the one-page summary of the production report for the entire episode: "8:30 to 9:15 AM - Co. delayed (45 min.) due to blinking light failure in Robot."

Fortunately, the workmen in charge of maintaining the robot had a spare neon unit on hand and were able to replace the malfunctioning ten-row neon unit with the new twelve-row neon unit. It is amazing that they were able to accomplish this major operation in only forty-five minutes. The speed with which the neon units were changed raises important questions about the mounting of the neon unit. It is unlikely that it was glued to the torso. Perhaps it was attached in some way to the back plate.

This delay forced the crew and stage hands to stay on the set until 7:40 in the evening. Bob May was the last regular cast member to be dismissed that day (at 6:15 PM). Only Ollie O'Toole, one of the two men who alternated as operators of the robotoid costume (Robby the Robot), was required to stay later. O'Toole was dismissed at 7:30 that evening.

The next episode to be filmed was "The Challenge." This episode began filming on Tuesday 1 February 1966. Throughout this episode, and for the rest of the series, the robot sports his new twelve-row neon.

[The new twelve-row neon unit seen in "The Challenge" scene B-88, filmed the first week of February 1966]