An indirect Crossover with Cory in the House and Hannah Montana via Wish Gone Amiss Weekend. The episode "Super Twins" takes place at the same time as the Cory in the House and Hannah Montana episodes "Gone Wishin'" and "When You Wish You Were the Star", as each show's protagonist wishes on the same shooting star.
The Hashimoto soda brand from the The Suite Life of Zack and Cody episode "Trouble in Tokyo" is featured in the episode "independANTs", and Mr. Hashimoto himself shows up in a recurring role, played by the same actor as in The Suite Life On Deck.
A poster for Tears of Blood, a band from Wizards of Waverly Place, is seen in the background of the episode "PerformANTs"
Z-Tech, maker of technology referenced in several other shows (such as the Z-Phone and the Z-Cube) is the setting for Season 3.
For that matter, the larger TGIF universe may be either connected or wholly a part/synonymous with the DCLAU regardless (in much the same way One Saturday Morning is connected to the DCLAU's animated counterpart), as the DCLAU is a Spiritual Successor to the old TGIF lineup to begin with (ABC was owned by Disney for much if not most of TGIF's existence and many of the production crew and companies went on to make many of the Disney Channel productions, including the first round of multi-cam live action shows, upon TGIF's discontinuation).
Ugly Betty: If so, would be the only series in the DCLAU not associated with any other show through actual production even if the TGIF universe is included (though still airing on Disney sister network ABC); apparently, some of the characters of Ugly Betty follow London Tipton's Yay Me! vlog!
High School Musical - Suite Life of Zack and Cody confirm it exists as a fictional movie series only within the DCLAU; their school puts on High School Musical as their actual high school musical, and Maddie refers to HSM star Ashley Tisdale:
Maddie: Some people even say I look like Ashley Tisdale!
Zack: I don't see it!
Madison High (an unaired pilot starring Dog With a Blog's G. Hannelius) explicitly exists in the High School Musical universe and thus would have been fictional in the main DCLAU as well.
Shows which are not in the DCLAU (aka Disney Channel independents):
Lizzie McGuire - The spiritual predecessor to the DCLAU, it has not been referenced in modern shows and was produced in a different format (a one camera setup as opposed to multi-camera) than the majority of DCLAU shows.
JONAS - In the series, the main trio is known as the Lucas Brothers and portray only expies of their real-world selves. This is in contrast to their appearance on Hannah Montana, where the explicitly named Jonas Brothers act as they would in real life.
Mr Young - Another Canadian import made by a non-Disney house.
It's generally accepted that any Canadian production or co-production on Disney Channel and Disney XD thus far exists in a completely separate canon from the DCLAU.
Thus far, no series produced prior to That's So Raven have been connected to the DCLAU. Likewise, no DCOMs which aren't directly adapted from DCLAU shows have been included in the universe (and it's possible even some of the DCLAU-adapted DCOMs might exist only on a quasi-canon status, or even in a complete non-canon status including the Wizards of Waverly Place movie).
Tropes constant across the DCLAU
All There in the Manual: While not necessary to enjoy the shows, the information hosted on Disney Channel's website fills in a lot of the backstory behind the plots and characters. Is useful if you're dropping into the middle of something both plot- and continuity-heavy like Wizards.
Bigger Bad: Almost all DCLAU Show's have a Big Bad, but on Wizard of Waverly Place, Gorog seems to be the devil of the universe.
Breaking the Fourth Wall: Done in kind of a weird manner in that often the characters will deliver a punch line and look directly at the camera while doing so, but not quite acknowledging that there is a fourth wall. It's just very weird.
California Doubling: Averted with surprising frequency in that a few of the series actually take place in California, but outside of The Movie filming virtually never leaves a Burbank soundstage.
Canon Welding: The three main founding shows of the universe (That's So Raven, The Suite Life of Zack and Cody and Hannah Montana) were initially not connected at all. However, when Disney Channel got the idea for That's So Suite Life of Hannah Montana, the shows were connected to be in the same universe (which itself had then been immediately established). As of this writing, Disney Channel continues to use this tactic to connect more shows to the universe.
Played with as well. In The Suite Life of Zack and Cody, Cody tells Max that she's a better dancer than the girl in the Missy Eliot video; both are portrayed by Alyson Stoner. Also in The Suite Life of Zack and Cody, Maddie believe that she looks exactly like Ashley Tisdale as Sharpay, to which everyone else replies with "I don't see it."
Comedic Sociopathy: Pretty common in most Disney Channel live action comedies, actually, though some shows have more of it than others. On the more sociopathic side of the scale you have Wizards of Waverly Place and A.N.T. Farm, and on the other you have Good Luck Charlie.
Cowboy Be Bop At His Computer: As children's programming has always been a hot topic, there will be frequent "experts" who have much to opine without actually having basic knowledge of the shows they're talking about. Take thesetwo articles - whatever the validity of their argument, their points are not helped with some very basic factual errors. Misspelling series names (iCarly is simply Carly, JESSIE is JESSE - and to boot, a screenshot from that show is attributed to Wizards of Waverly Place), much attention has been given over to shows that have been canceled, etc. Much of this would have been avoided if only they visited the shows' IMDb pages.
Crisis Crossover: The specials That's So Suite Life of Hannah Montana and Wizards On Deck with Hannah Montana.
Red Skies Crossover/Cross Through: The Wish Gone Amiss Weekend, in which, rather than interact, three shows were impacted by the same event (a magic shooting star). There were also the Lunar Eclipse episodes of Kickin' It ("Invasion of the Ghost Pirates"), Lab Rats ("Principal from Another Planet") and Mighty Med ("Night of the Living Nightmare"), which all aired on the night of an actual lunar eclipse and featured paranormal occurrences thanks to the eclipse.
In the That's So Raven episode "Checkin' Out", Raven uses a device called a Secretech. The Secretech previously appeared in The Suite Life of Zack and Cody episode "Forever Plaid", where London used it in class to check her schedule.
In the Hannah Montana episode "Would I Lie to You, Lilly?", Miley, Lilly and Oliver have a class trip to the White House, which uses the same sets from Cory in the House.
Continuity Overlap: The single episodes in each series' that are a part of the Crisis Crossovers usually have an impact on other episodes in the crossovers, so much that it becomes downright confusing if you miss part of a crossover. Examples of this are Raven missing her flight in "Checkin' Out", causing her to stay in Boston in "That's So Suite Life Of Hannah Montana", and Bailey and Alex cheating in the Hannah Montana tug-of-war challenge in "Cast-Away (To Another Show)", which leads to Bailey trying to find another way to get concert tickets in "Double-Crossed".
"Do It Yourself" Theme Tune: A solid Disney tradition given how many shows promote musical talent, though there are notable exceptions (both Suite Life series and Shake it Up being some of the most prominent subversions, though the latter's is still sung by Selena Gomez).
Executive Meddling: Most prominently and visibly, when all of the shows are mandated to have a common theme or plotline to promote said common theme (a "mystery weekend" where all of the shows have plots centered around solving a mystery or a "vacation getaway weekend" where all of the shows focus on the main characters getting away on a vacation). Don't be surprised if at least one of the shows puts a serious Lampshade Hanging on how ridiculous or out of place such a contrived plotline seems, if not a more blatant Take That (the Scooby-DooShoutOuts on "Whodunnit Up?" being a borderline example for the latter).
The various Crossovers being another example of Disney Channel Executive Meddling in practice.
So Random!! an example of an entire show being created/ReTooled half because of Executive Meddling (the other half due to the departure of Sonny With A Chance star Demi Lovato - really, the executives were just trying their best to salvage the situation)
Fleeting Demographic Rule: With few exceptions (presently only That's So Raven and Wizards), every series has ended at about 65-75 episodes. Hannah Montana did come very close, though.
Good Luck Charlie has been renewed for a fourth (and likely final) season (now the third series to likely reach 100 episodes), potentially indicating that 100 episodes may be the new benchmark.
High Concept: With only one real exception (Good Luck Charlie), all of the shows in the DCLAU have followed the high concept formula, and a few (That's So Raven, Wizards of Waverly Place, Dog With A Blog, Lab Rats,Crash & Bernstein, and Mighty Med) are all completely fantastical.
Loads and Loads of Characters: Obviously for the DCLAU as a whole (and regarding the combined rosters of crossover events), but many individual shows in the DCLAU tend to have large casts as well at least when including recurring roles.
The Movie: Wizards, Suite Life on Deck and Good Luck Charlie all got a television movie. A Jessie movie has been approved. Good Luck Charlie also got two hour-long specials and so did A.N.T. Farm. Shake it Up: Made in Japan is somewhere in between with a 90-minute air time; although not promoted as such, it's effectively a television movie too. And in at least one case (Hannah Montana), The Movie was an actual theatrical release.
Our Presidents Are Different: President Martinez, to fit into the standard sitcom mold, is both a President Personable and a President Buffoon.
Guest Appearances shouldn't mean anything. After all, Maddie Fitzpatrick and Ashley Tisdale apparently both exist in the DCLAU (and apparently, only Maddie herself ever noticed any resemblance between herself and the High School Musical star).
Running Gag: Offering fruit juice sweetened cupcakes (mostly in the more recent shows).
Running Gags in general: after all (and excluding the crossovers), running gags are what link the universe together in the first place. And of course each show will have its own set of running gags.
Shouldn't We Be in School Right Now?: For the most part played straight in most series, but many shows (Wizards of Waverly Place, Shake it Up, the second season of Austin & Ally), the school setting actually features very prominently if not factoring into the plot in some fashion roughly Once an Episode. A.N.T. Farm is the most notable and largest Aversion as the high school and its social dynamics are the main focus.