The programming for a television station is typically stored in a large "refrigerator" containing data, video tapes and other media. Tape Switch occurs when it's 4 p.m. and Tony in the broadcasting booth accidentally puts in the hair gel commercial instead of the Gillette razor commercial that's supposed to be in there at 4 p.m., and you get a "blip" of the wrong commercial, or maybe half a commercial, then a complete commercial for something else. The same "blip" occurs nowadays for a different reason with some cable companies, who overlay their own local commercials in some breaks; the blip happens if Tony at the cable company is a second too early or late in flipping the switch. Most large broadcasters now run from media servers allowing for a high degree of flawless automation when it works, luckily they're fairly reliable. But don't consider this a Trope Breaker just yet, as many smaller outfits who have been around long enough (server based transmission co-located with other networks much like web service providers is more the rule than the exception now for newer broadcasters) may still be running their channel out of the old tape fridge.
This also happens in radio. When it cuts to the same commercial ("Hey, Tony, I guess it was the right tape after all!"), it's Repeating Ad. Often the commercial they yanked may be more intriguing than the one they put in, especially when it's the local cable operator cutting away from the network feed for local commercials (usually to advertise the service you are already watching it on).
- The Sci Fi Channel (now called Syfy) frequently made this mistake with a certain video game production school. It would show one commercial, then two or three seconds of a creepy CGI skeleton guy.
- At random times during the day, the Bott Radio Network in Kansas City will have the announcer say "SIN", and then cut to a different commercial. No one seems to know what commercial that's supposed to be.
- It's not a commercial, it's a command, so, you know, start sinning.
- During LOST's 4th season, some areas would regularly see a local commercial touting social security (or home security), just before the end of the commercial break. It was always just before the show resumed, and only the last second of the commercial was shown, making the word 'security' muttered by an aging woman the unofficial prompt to 'find your seats, the show is about to begin'.
- A variant of this has cropped up in modern cable television: About every half-hour on cable stations, the channel's commercials are pre-empted by the cable company's commercials. If you're lucky, they'll sync up correctly. A little less lucky, and the network's commercials will be interrupted in mid-commercial or the company's commercials will end early so that you can see the tail end of the channel's commercials. Even less lucky than that is when the company's commercials end late...
- This is unintentionally subverted on the National Geographic Channel as broadcast in Israel, where it is broadcast on cable based on a feed from other European countries. Most of the time, the cable trailers completely overlap the commercials, and if they don't the cable company broadcasts some local wildlife footage to make up for the gap. Many times however, they forget to pre-empt the commercials entirely. Many viewers of the channel (few as they are) actually enjoy this, because it gives Israeli viewers a chance to see actual commercials from other European countries, thus inadvertently fulfilling National Geographic's "cultural-exploration" theme! It helps that these commercials are often in Dutch, Romanian, Turkish, etcetera.
- The juxtaposition of the ads makes the teen's comment rather interesting in context.
- Viewers in New Zealand on all platforms occasionally get blipverts changing between the national and regional advertisements.
- ABC Family is a big offender, especially when you're watching shows like The Secret Life of the American Teenager. It can go from "before ad ends, insert local ad, end with last 2 seconds of the original ad", "original ad starts, interrupt a second later with local ad, end late, rest of the next original ad continues with a first few seconds missing of the ad", or a combo of both. And it doesn't get spared at all, no matter what pay-tv provider you have, it will happen.
- Nickelodeon sometimes have this by a milisecond.
- There's a few rotating network promos just before the last segment on NBC Nightly News; at least one local station runs a brief weather update over it.
- Many years back, a hilarious example from a UK commercial station had them running a promo for a steamy drama called Bouquet of Barbed Wire. As the actors chewed the scenery, unfortunately the soundtrack came from The Muppet Show and Kermit the Frog.
- This kind of mistake is actually very rare on UK television, thanks to automated time cues.
- Just for historical accuracy, what happened was that an actual episode of (not a promo for) Bouquet of Barbed Wire was being broadcast when the soundtrack was suddenly replaced by the Muppets. What had happened was that the transmission suite had begun previewing a Muppet Show promo, not realising that a patching fault was causing the audio from whatever they had on their preview bank to be broadcast to the nation.
- Cartoon Network often did this on intershow breaks, depending on the area, where a promo would appear before getting cut off by a local commercial put there by your cable provider.
- At least once on TNN (now Spike TV), during a rerun of Hee Haw, a commercial for a Conway Twitty compilation album was in one area replaced with two promos provided by a cable company, one for Bill & Ted's Bogus Journey and the other for The Bob Newhart Show. Unfortunately, due to a tape error, the audio for the Twitty commercial was played in its entirety over the silent cable promos, resulting in some Soundtrack Dissonance.