Acting for Two: Chespirito in the Crossover; Carlos Villagrán in a flashback with Quico's father and baby Quico; María Antonieta De Las Nieves as both La Chilindrina and her "Bizcabuela"; Edgar Vivar as Sr. Barriga and Ñoño (sometimes even Talking to Himself); Florinda Meza as Doña Florinda and look-alike niece La Popis.
The Danza: Chespirito liked to do this, because he felt the actors would be more connected to their characters this way. Same went for many of them when they played extras in El Chapulín Colorado, which used the same cast.
"...Florinda Meza as Doña Florinda; Ramón Valdés as Don Ramón..."
In later episodes, Maria Antonieta de las Nieves (La Chilindrina) as Doña Nieves.
Franchise Zombie: After the departure of Quico and Don Ramón the show substantially dropped in quality, but it still went on for approximately ten more years. The reason for this was that back in the 80's, the channel where the program aired enjoyed a virtual monopoly on the Mexican TV airwaves, making it possible to air whatever it wanted without risking much ratings.
Missing Episode: Some of the original early sketches. And depending on what country you're in, many episodes can be missing from syndication. Brazilian TV network SBT (heavily associated with the show, having aired it almost nonstop since The '80s) since 2012 started to air some "missing episodes" never seen before (or which haven't been shown in a very long time) in the country.
Despite the success of El Chavo, the series had its detractors, mainly for their slapstick scenes that some considered as "violent" and harmful to children.
Ecuador takes this trope Up to Eleven. Ironically, Ecuador being the first country where the program was successful outside of Mexico, is the same country where the strongest criticism appears. Some of the comments against the program come from Ecuador and studies on the incidence of violence on TV (where they include El Chavo as an example) are from Ecuador.
Reality Subtext: The last batch of Chavo episodes were classroom sketches. This was in 1992, at which point Chespirito was over sixty, and not as able to do his slapstick routines as he once was. The classroom scenes could be done with everyone sitting at desks.
Recycled Script: Some scripts were done as much as four times. Sometimes, with the very same characters in the very same roles.
Talking to Himself: In the later seasons, (after the departure of Ramón and Quico) most of the cast actually played two characters. And they were needed to interact each other using split image. In the Crossover with El Chapulín Colorado, even the titular character needed to do it.
Throw It In: Many bloopers made it to the final edit. Sometimes this was because they were funny or the cast used them to their advantage. In one episode, after a typical confrontation with Doña Florinda, Don Ramón angrily throws his hat, and it accidentally goes through Doña Florinda's door just as it closes. Don Ramón continues his snit fit but briefly pauses to knock on the door until one of the other actors lets him in to retrieve it. (See it here.) No one breaks character, which makes the scene funnier than if it had gone as planned. Other times, production problems that should have caused a stopdown didn't. There is one early show where a loud thunderstorm is obviously going on outside the studio, and yet no one mentions the frequent thunderclaps that can be heard over the dialogue.
In one of the versions of "Que Bonita Vecindad", Ramon Valdez clearly messes up a dance move, but it was left in the final version.
Throw it ins often got through because of schedule deadlines rather than for being funny since Chespirito was known to dislike improvisation.
The Internet's reaction after Ecuadoran congresswoman Rosana Alvarado's tweeted negatively about Chespirito on the day he passed away.
The Brazilian actress Paula Braun criticized the commotion with the death of Chespirito saying she does not understand this reaction. This quickly angered many fans which started to hit back. After all the controversy, she said it was a misunderstanding and she likes El Chavo too.
Godínez was technically a recurring character, but still unimportant enough that actor Horacio Gómeznote That's Horacio Gómez Bolaños, the younger brother of Roberto Gómez Bolaños, AKA Chespirito appeared as other characters once or twice, such as in the Acapulco special where he appeared as a waiter in the hotel the cast was staying, as Godinez hadn't gone on vacation with them. In one case, Horacio Gómez even appeared as both Godinez and a restaurant manager in the same episode, with no mention of them being related.
Also, famous soccer player Pelé once phoned in Chespirito to ask him to make a movie of the show and even offered himself to appear in it, but Chespirito declined as he didn't support the idea of having movies of shows you can see for free on TV.